First thing to do is check the fuse.
If fuse is blown, replace. (You might buy 2 just in case)

Bill,

Thanks for the advice. Once I found where the fuse was, I changed it and the mower started up. However, when I pulled the electric PTO knob, the mower died. Yep, another blown fuse. Should I be looking for a short in the pto wiring?

That or a "dead" (shorted) PTO clutch.
Unplug the PTO and see if it happens.
If it still does, the wire to the PTO has a short. If not, probably the PTO is dead.

Do you have a Voltmeter?

So here's where I stand...new fuse, engine starts and runs fine. When I pull the electric PTO, it does not engage but the mower continues to run. I unplugged the PTO and the exact same results, mower runs, no PTO engagement.

I do have a 12v test light. There seems to be no power going to the PTO. I don't think any power is going out of the PTO switch either, but I'm not sure because there are a number of wires and I can't decipher the wiring diagram in the book.

So, what's the next step?

Just a bit confused here-
With the PTO plugged in, it died because the fuse blew when you engaged the blades.
And now it doesn't, but the blades don't engage when they should?
Have you rechecked the fuse?
What's the Sears #? It should be something like 917.xxxxx

Assuming the fuse is still good, use the test light in place of the electric PTO clutch. When you engage the blades, the light should come on. That would indicate power to the PTO.
An OHM meter would allow you to check the coil inside the electric clutch for being OPEN or to see if it has the "nominal" 2.5-3.5? Ohms resistance. (somewhere in that range)
Do you have a big enough mailbox/ fast enough internet connection to receive a 2-3 meg pdf if I can find the schematic? Don't forget the 917.xxxxx or whatever number, so I can get an idea of what you have.

You're right Bill. Previously the fuse blew and the engine died when I engaged the PTO. Now, nothing happens when I engage the PTO. I used the light and tested the wire going to the PTO. There is no power. I don't have an OHM meter.

My model is 917.272420. If you can find a schematic, please send it on or post a link to it.

I appreciate your help.

Remove the hood, look closely at the wiring harness
you have to unplug going to the headlights, see if it is molten, if so repair it, especially if it has 2 black wires
going into the 1 terminal.
If all looks ok there, look at the wiring harness at the
steering gear, another possible bad area.

Fish

Here's the latest. I replaced the electric PTO switch but that did not fix the problem. The PTO clutch still refuses to engage and then the fuse will blow. The clutch is receiving power.

The new development is this. I have found a sheared metal ring loose around the shaft at the top of the PTO clutch. It's a thin tapered ring about 3/16" tall. It would seem this is the problem so what am I looking at for repair? A new PTO clutch or, if I remove the PTO, can I just replace the ring?

"Now, nothing happens when I engage the PTO"
"The PTO clutch still refuses to engage and then the fuse will blow. The clutch is receiving power."

That indicates the PTO is Shorted. If the PTO is disconnected and the tractor doesn't blow fuses, that would tend to isolate the problem.
If you had an OHM meter, you could check the resistance of the PTO coil.

"I have found a sheared metal ring loose around the shaft at the top of the PTO clutch. It's a thin tapered ring about 3/16" tall. It would seem this is the problem..."

Not exactly sure what you're talking about, but it doesn't sound good.Sounds like time for a new clutch to me.