The linkage on my Jubilee is so slopy, worn, that the next time I take it apart, I'm going to ream out the piviot points and make a bushing to fit. Try to make the round places round again.
I also made a 1/2 inch drift pin to help bring my adjustments close enough to work.
Face it, 60 years of wear and rust created by no vent in case, takes it toll.
I also had to rebuilt my pump and installed a pressure guage. It's possible there are more than adjustment problems here.