Toyota Repair: Clutch issues, clutch cylinder, clutch release

Question
Hi, I have a 1990 Toyota MasterAce Surf van with a 2C-T diesel turbo engine.
I started having clutch change issues a while back and took it to a garage whom replaced the master clutch cylinder.  After a short period the problem returned, where the gears would progressively get tight to change, the issues always seem to start when dropping from 3rd to 2nd gear.. then progressively gets harder around all gear changes until changing becomes impossible.  Alas during the cylinder change and the recurrence the garage I used went out of business so I took it to another garage whom told me some master bolt was replaced that shouldnt have been and that it was too long and they shortened it.. again, after a hundred km's of driving or so the problems started reoccurring...after talking to the garage again they wanted to replace the entire clutch.. being that there was no slipping or anything else I took it to another garage for another opinion who told me the compression wasnt happening around the cylinder then found some sort of bolts that were loose, so they tightened them and then again the clutch worked fine for a while like a dream and then started getting tight again.  What I have found with my own experimenting is that even when the clutch is solidly locked, if I take a spanner to the bolt that the clutch pedal releases up in to and move it, even one fraction of a millimeter, the whole thing frees up and I can change gears nicely for a bit and then gradually gets stiff again so that I cannot change gears... Can you please give me some assistance as to what I should do, I have spent ALOT of money at different garages for different solutions and have got no joy.  I thank you kindly,


Answer
Possibly a hydraulic fluid leak, does the fluid in the master cylinder reservoir go down? If not then there may be a problem with the clutch release cylinder on the transmission, I don't think there is a problem with the clutch itself because if that's the case the problem would be there all the time.