Remove the transmission and check the support bearings on the shaft. If they are free, the transmission is toast and needs to be replaced, it is not serviceable.

I think the transmission is serviceable in the right hands. That is a very straight forward tranny and parts can be bought for it individually.

I would guess the wheel clutches may be malfunctioning. What happened to the mower that you have all these problems all of a sudden?

Derbydad, you need to go to this link and examine the schematics of your mower and decide how much further you want to go.

Its hard to diagnose a problem like that when one cannot physically see and hear the problem.

Here is a link that might be useful: Toro parts viewer

Thanks for the replies.

I did some web searches and found that individual parts for the tranny are available, but first...

- What happened to the mower that you have all these problems all of a sudden?

I don't know. I pulled it out of the garage and those were the symptoms. My son uses it for neighborhood lawns and when I asked him about it, he said the last time he used it he noticed the SP feature didn't work and that the wheels didn't turn backward, so he was no help.

- I would guess the wheel clutches may be malfunctioning.

Both wheels at the same time? Is there some part that is common to both wheels that would prevent either of them from turning backward?

- You need to go to this link and examine the schematics

Thanks for that link. I had already looked at the schematics, but nothing I saw there helped me diagnose the problem. I'm reluctant to start throwing parts at it...I'd rather narrow it down a little more first. For example, the schematics don't tell me if the tranny should turn easily in either direction when turning the pully on top. If I knew that answer, it might lead me in a certain direction. I also didn't see a specific listing for a "wheel clutch". Can I assume it is made up of multiple parts?

- Its hard to diagnose a problem like that...

Is there any other information I could provide that might help?

Again, thanks! I'd appreciate any other help you could offer.

Check the transmission bearing that the pulley sits on. Its pressed onto the inside of the top cover. Its a ball bearing type. If its seized that may explain the belt and wheel problem.

I would think that both wheels clutches being bad would be odd. So probably not those then.

I'm gathering it's a front wheel drive. Do they have the wheel clutches like PP? I wouldn't think so.

Too answer one question: Yes, the pulley on the trans should turn freely (With the wheels raised off the ground.) The roll pin that runs thru the 37 tooth bevel gear (in the trans) can and does sometimes back out and will jam into the transmission case locking it up.
The 13t wheel pinions (on the axle) can also be put on backwards causing it too lock. The pinions are stamped "L" one side of the gear and "R" on the other side. The appropriate marking should be visible when reassembled. ie.."R" on the right side of the mower and "L" on the left side (when viewed from the operators position.)

buttlint: Thanks for your detailed response.

The 13t wheel pinions have not be taken off, so I doubt that's the issue.

I will look more closely at the roll pin tonight and see if it looks out of position. I assume it can be put back into it's rightful position, correct?

Should the pin be the problem, it can be tapped back in, but keep in mind that it worked its way out once already. I cant recall whether its a solid or split pin but if its split....you can take it out and spread it a little for a tighter fit.
It never hurts too remove the wheels and grease or oil the axle and pinions. Toro didn't make it easy maintaining that drive system by not providing any zerk fittings, but it still needs periodic greasing.(or oil) Without attention the pinions can lock up on the axle and cause all kinds of other problems that cost some bucks too repair. If your son does lots of cutting and its never been done....it needs to be taken care of. (You can check the pinions for "L" and "R" marks at the same time.)

The one way wheel problem is not a problem, as that's the way it works. Since it is self-propelled, you wouldn't normally try to pull it back, unless you bear down on the handle to lift the powered wheels off the ground.
Most lawn mowers sold to home owners are not designed for much more than a weekly mow. And, since your son does lots of mows every week, the life span of the mower has been shortened considerably!
The transmission parts, or a new tranny, are quite expensive. You must consider if it is worth repairing, or just buying a new one! Many youthful lawn mowing businesses have been shut down by the kid using the family mower, and wearing it out much before its time!
Now is the time for the son to learn the facts of life!
To wit: Using the family lawn mower for contract or friendly mowing jobs, will not gain favors from Pops! So, that said, have the son buy a heavy duty lawn mower that he can use (or buy the first one for him) for his business. He must save part of the cash he gets, to buy stuff he needs, and that will teach him something more than what he learns in school! And also, he must learn that he needs to save money to buy the new one, when the old one wears out.
I learned long ago, that money talks. And, spending it on the latest fads usually begets you nothing more than being broke most of the time! And/or, on welfare!

I have the lock-in-reverse problem with a 2-year-old 20092 Personal Pace mower. Problem developed over a period of a month or so. Not a problem on hard ground, so it's a clutchy-feely problem of some kind. Toro service manual for this model and s/n does not appear to be available on line, but the parts viewer does cover it, so may be of help. It's either the transmission or one or both (I think both) of the gear case assemblies.

This might help in some situations...front wheels would only turn about half a revolution on my Toro. When I removed the front left wheel, which had been broken previously, I found the broken piece of plastic had fallen inside the wheel and was stuck in the cogs of the gears so that the wheel could only turn so far. Similar problem occurred with a Toro I borrowed while having carb cleaned on mine - except this one was missing about half of the cover on the back of the front right wheel, allowing the gears to become so packed with dirt and debris that they wouldn't turn at all. Cleaned with a steel brush and it worked fine afterward. Well, til the drive belt broke, anyway. If it's not one thing it's another...

Check that the belt is not jammed with some debris, also check the drive wheels for plastic gears, which will wear against the metal pinion gear, removing the tips off the big gear. I found a conversion to metal gears on ebay thats nice. It may not be the tranny as I had both of those conditions previously and it wasnt the powertrain.

I replaced the transmission assembly on my Toro 2007 last summer. Make sure you have a good set of snap ring pliers.

I had the issue you've described a few years ago. I pulled the wheels, eclip and pinion gear off. Cleaned and lubed with antiseisze, worked great. I did replace the pinion gears as they were quite worn so not sure which corrected the problem.

I wash the machine, but found that high pressure water like from my pressure washer can penetrate bearings and cause premature failure so I just use a hose mainly, and after it dries in the air a while, I use a little water displacement formula 40 (wd40) or silicone spray to re-lubricate and protect the metal and mechanisms.