Finally got the tractor back together. Only took four splits - feels more like five.
The first time I put it back together, it seemed OK - until hydraulic fluid began pouring out from the starter. Split it again and replaced the 50-year-old rotten looking hoses in the clutch housing, and figured that would solve the problem.
Put it back together and stated it - still pouring fluid out of the clutch area. Got under and looked in while my son cranked it - oil coming out near the high pressure fitting. The new gasket between the front cover and trans housing had blown out because I had missed an O-ring.
Split it again. Found a suitable ring and put it back together again. Still leaking.
Went over the parts in the exploded drawing. The only culprits left were several O-rings in the fittings and the one I just replaced. Ordered all new rings and another gasket.
Got the parts Friday and split the tractor again. The O-ring I had put in slipped out of its' counter bore and got crushed. Replaced all the O-rings and the gasket, and carefully reassembled it. No leaks.
Mowed the firebreaks - and knocked the muffler apart on a dead tree branch. So, off to Farm and Fleet for a new muffler.
At least I can split the tractor in under three hours now...
Update 8/29 - last Tuesday I decided to go over the firebreaks again, as they need to be trimmed at least once a week to keep them neat. Made it around the west fields and about a third of the way around the east side - and the clutch locked up. Had this happen once in a Chevy C30 panel truck - bolts backed out of the flywheel and jammed the driven disc. I'll have to split the thing yet again to find out for sure, but there are no loose parts in the clutch housing, at least.
Oh - and about a quart of hydraulic fluid was in the bottom of the bell housing. Leftovers from the last time, or still leaking? This from about an hour of running.
Picked up a new muffler and a bucket of fluid - muffler in place, fluid waiting for a working clutch.
Since the firebreaks are mowed, it can wait a while - perhaps next weekend, which is a long one...