Let me begin by thanking you for running this board! Any group nuts enough to try and keep 50 year old RVs on the road needs all the help they can get.
I Know about the grease cup. In fact it is in part why I had to pull my cradle. Mine was missing the grease cup and the zirc pittings for the shaft on the bottom of the transazxle were so covered with road grime that they were not visible. clutch was completely seized and would not engage. I got things all cleaned up and lubricated, added a grease cup and even replaced the slave, all the hard plumbing and flexible hose, and rebuilt the clutch master (leaving out the check valve.).
The cup I was talking about is the receiver for the bottom end of the shift lever. Mine has a square head set screw safety wired into place. I wondered if it was adjustable, or if there was an adjustment on the inside of the linkage under the side access cover.
I bled out the clutch system and adjusted as per the manual and only have 7/8″ of travel on the shaft arm. I wonder if I should have more….