The bellows kit makes it a cleaner easier deal. What it really important is cleanliness. Go ahead pull the hydro, clean it up well and give it a try.

Years ago I had a Scotts with a Peerless VST and contemplated the bellows kit. It worked great.

While searching I did come across the following info. I didn't try it nor can I take credit but if you don't want to do the bellows kit, which I REALLY recommend, this info may help you...

"I think you have a peerless VST tranny. If so, you can pull the battery and see the top of the tranny.

When you look down at it you will see the drive pulley and fan on the tranny. Also, there are 2 rubber plugs.

To the right is a plug to the gear compartment. A probe to the bottem of this area should have 1/4 to 3/8 inch of gear oil on the bottom of the probe. However, This isn't your problem.

Under the back of the pulley/fan is a smaller black rubber plug. This gives access to the hydro fluid and should be completely full. The best chioce (IMO) is to drain the old oil and replace with mobil 1 15W-50.

As to those screws with a pin in the middle (known as security screws). While a special bit for them exists, I use my dremmel and a cut-off wheel to make a slot in the screw head for a normal screw driver. But I had to remove the tranny to do this, but it made pouring out the old oil quite easy. The hydro takes 1.5 quart (approximate) to refill with oil. If the screws were removed, the rubber bellows must go under the steel plate with the small hole. The hole can be used with a probe to be sure the bellows is covering the right amount of oil. A probe should reach from 3.25 to 3.5 inches deep from the steel plate. HOWEVER, THIS DOESN'T SHOW HOW MUCH AIR IS IN THE TRANNY, which makes the check useless."

There are several nice things about the kit, including the instructions and the security bit for the screws. The bellows itself can likely be cleaned and reused. In my opinion, you do a better job pulling the assy and doing a full clean up first. The "service" is likely to be successful if the old oil hasn't broken down too far to the point internal issues exist.