CAT D3 Steering issues

Hello Folks, Just working with a 1978 79U1-UP CAT D3 which moves forward and back, with power, the 3204 sounds good, no smoke, fired right up after sitting for years. Right Steering/Brake pedal brings right turn very well, but Left compliment brings machine to grumbling halt and produces to No Left turn. Apparently, the shop guys have addressed similar operator complaints a couple times in past years, and I guess fixed the issue by fooling with the easier stuff, cleaning up the control value, maybe adjusting the rod back to the steering clutch housing. They didn't share notes but seem not to have spent much on parts or talked of the big job of pulling the clutch out. I guess it may be possible they didn't fix it, though apparently someone went off an used the machine at least on a minimal job. You pretty much need to steer...!? I guess my question is what's the likelihood that the clutch stack (or stacks, the right also) are stuck up, or a big mess inside, causing this symptom? If so, despite the brakes being anything but power brakes, shouldn't it be noticeable, more lurching in some way during start/stop, just moving straight forward or reverse, IF the steering clutches are all gummed, mostly disengaged all the time? We're still talking major aspect of the power transfer to the track, aren't we? And further, are people still rebuilding these clutches, parts still available, etc? thanks for your comments in advance. Sorry if similar issues are already discussed somewhere that I haven't seen (yet).