D5B Dozer clutch trouble?

I',m new to the forum, a fair mechanic but never worked on heavy equipment other than a tractor.

Just inherited a Cat d5B, 1985 Serial number 44x. Had sat in the barn for 10 years because the left track tensioner was shot. Split the track and rebuilt that along with the two lift cylinders (oil pouring out of the completely rotted seals)
Dozer has ~ 4,000 hours on it, runs great 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 nothing happens until I am at the end and the track immediately brakes
As far as I know everything was working fine when it was parked 10 years ago

BTW, transmission is a Power Shift

Dad had the right side drive rebuilt when he bought the dozer in 2000 (though I don't know exactly what the problem was), but I don't think he did anything to the left side.

could this be a stuck clutch? I think it's a dry clutch
any tips to diagnose whether it is a control valve stuck, and adjustment? or where to start?

I'm going to buy the service manual from Jensen, but am looking for some advice on how to pin down the problem, where to begin and what I might be up against

If it is a dry clutch , there's a real good possibility of the clutches rusted together. Especially if it pulls the engine down dramatically
while pulling on the steer lever. Being a Deere mechanic for years , I'm not that familiar with the Clatterpillars. Machines stored for long
periods have a tendency to rust clutches especially if parked outdoors. Moisture is a killer for machines left untarped. Deere dozers were
notorious for getting water into the clutches if left untarped.. Sounds like to me it needs to come apart at least to look for rusted linkages if
not stuck clutches.

Thanks for the thoughts Roy. the dozer was stored in a dry barn for those years, so I dont think the weather would be an issue, but i suppose they could stiff be rusted...
Once I get the manual and know what I have to look for I will have a better idea what to look at first.

I'd like to eliminate the "easy" things first before I start pulling everything apart. Don't even know if I can do that without special tools and such

I think the 44X was powershift and it has a wet back end, make sure there is oil in all compartments, adjust the clutch first and the brake last, by what you are saying it is disengaging at the end of the stroke so the clutch is not stuck, it may be out of adjustment, after you check the adjustments work it for a while and see if it improves.
AJ

Thanks AJ, I should get the manual today and be able to confirm wet or dry and how to adjust. I wont be able to be back to the dozer for
some weeks due to other work, but Ill update the post as soon as I make some progress

Got the manual for the dozer and confirmed that it is a wet clutch, so I beleieve that it is very unlikely that the clutches are stuck and rusted together.

With the Power shift and the fact that it has a torque converter and not direct drive connected, i suppose that when I am in gear and both drives connected and the brakes on the torque converter provides the "slip" so the dozer would never stall out.

I will go through the clutch and brake linkage and adjust as needed. then i suppose I need to get in and check the hydraulic control valve to make sure that the left control is pushing the clutch throw-out properly. hopefully there is a port that I can install a pressure gauge and confirm the control halve is working and not stuck.

I'll post again when I have had a chance to get back to this.