Case 550G Track won't stay engaged

I recently bought a Case 550G Long Track. I've ordered a service manual, but don't have it yet (said two weeks out), and have zero experience with this type of dozer, so I'm looking for ideas. The dozer cranks and runs fine, the undercarriage is in fairly good shape, sprockets actually look almost new. It shows only 1800 hours, but I'm not really trusting of hour meters on used equipment. It pushes dirt and brush okay, (which is why I bought it), but the right track speed control doesn't want to stay engaged. (When only one track has power, the pushing "ain't so much".) The lever doesn't move, but the track seems to pop into neutral every few seconds, until I "fiddle" with the lever. I took the seat off, and adjusted the tension on the track speed control per the owner's manual. The spring scale I had showed it was only about 2 1/2 lbs pressure to shift from neutral to high or low, so I adjusted it to about 8 lbs, (at the high side of the recommendation in the manual). I am still having to jiggle the lever on that track almost every time I shift from forward to reverse, or shift that track from low to neutral or neutral to high, or use the brake on that track.
I note that the "ear" on the linkage from the lever (under the seat, near the front) actually touches one of the other linkage rods when in low range, but there's not a "dent" or mark on the rod that suggests it is hitting it really hard or staying there when the dozer moves.

I know this is a long winded explanation of the problem, but while I started on this forum today, I break a lot of stuff, (trucks, tractors, loaders, etc.) and on those forums, know the better the explanation of the problem, usually the better folks are able to point me in the right direction.

Any suggestions appreciated, thanks.

Case 550G Track won't stay engaged