dthurk, You may not have to get into the starting clutch inside the engine. I would first clean up the starter and do the ground modification. There is a couple of threads on doing this in the General Discussion heading, then the Quick Reference section.
Removing the starting motor is not difficult, it is only held on by 2 bolts and a large wire coming from the solenoid. Follow the tread on cleaning, don't use steel wool inside the motor, remember where the thin spacer washers go on the armature, check that you re-install the gear the same way it came off, and polish the commutator bar with Scotchbrite.
The method used in the second thread on the ground modification seems a awkward, finicky way to get a positive ground from the bare brush terminal to the motor case. I have been using a 2" piece of braided copper wire and two ring terminals to transfer the ground. I crimp and then solder the terminals. Be careful when soldering braided wire, the solder will want to wick it's way up the wire and then you lose the flexibility of the braid. Braided wire can be hard to find. I found a coaxial cable with a copper braid that I doubled up. Other sources would be old or discarded starting motors or other electric motor brushes.
When you have the braid made, find an appropriate spot on the rear motor cap that is less seen and more importantly has a flat spot on the inside of the cover. Drill a hole thru the case and insert a 8-32 or so machine screw thru the braid ring and poke thru the hole. Install a machine nut on the screw. Then attach the other ring to the bare brush terminal if you have not already done this. Make sure there is no interference with the braid and the commutator shaft and install the two long bolts holding the case together. Note: There are index marks to show alignment of the case halves, or use a Sharpie to make your own before you take the case apart. Cut off the excess of the screw past the nut and peen the end just a bit.
Hook everything back up and you should be OK for another 29 years. The whole process the first time will probably take 3-4 hours. The next time you can probably do it in 2 hours.