JC- I think we're there in terms of identifying the problem. Clutch disc thickness (both sides of middle steel plate) is less the 1/4". No way to get calipers in there but remaining thickness is nowhere near 3/16. I may try an adjustment to buy time, but it's worn out.
I also read the other post you suggested. Since my
PTO and back wheels BOTH lose power at the same time, I don't think it's the
PTO override. Also, when the engines cold and the
PTO level is disengaged, the tractor still takes a long time to get moving. It's a strange sensation sitting there in gear with the clutch out not moving.
The transmission clutch adjustment is straight forward - Mechanical on the outside.
I have an operators manual, but I'll pick up a service manual. Is that the book I need? I also see shop and parts manuals available on line. Service manuals are available for < $200, so that sounds like a good investment.
Thanks for the sage advice. I'll update!