Cat D5b Clutch problem

I'm new to the forum, a fair mechanic but never worked on heavy equipment other than maintenance on a tractor. Just inherited a Cat D5b, 1985 Serial number 44x from my dad. The dozer sat in the barn for 10 years because the left track tensioner was leaking and Dad didn’t want to lose the track. I split the track and rebuilt the tensioner along with the two lift cylinders (all the oil poured out of the completely rotted seals after the first time I lifting the blade) Dozer has ~ 4,000 hours on it, runs great and is very clean but... When I pull the right clutch lever the track slowly disengages and eventually brakes, nice and smoothly When I pull the left clutch lever, I pull... and pull...and pull… and nothing happens until I am at the end of the travel and then the track immediately brakes As far as I remember everything was working fine when it was parked 10 years ago BTW, transmission is a Power Shift with a torque converter I pulled the panel under the front of the seat and it seems that the linkages are all connected and looked to be evenly set ( I didn’t have the manual so I was just looking to see the right and left appeared to be working and moving the same) I originally thought it was a dry clutch, but got a copy of the service manual and see that it is a wet clutch, so I don’t think it could be rusted or stuck together… and it doesn’t appear to be slipping Other than checking and adjusting the linkage is there any quick checks I can make to help determine the problem? Is it possible it’s a stuck control valve for the left clutch? Any way to check that without pulling everything apart? I won’t be able to get back to the dozer for some weeks due to other work, but wanted to start planning out the troubleshooting Any tips on where to start would be appreciated greatly