I have a Komatsu D20A-6, not sure if our dozers are similar or not but here goes - I venture to guess to start by loosening the right steering break band. Adjust them so that when you pull back both levers, both levers stop at about the same distance out.
When you back up and the track is locking up, does the engine want to stall? If so that would be a pretty good sign that the steering break is catching in reverse, OR someting is binding somewhere.
Now if when you back up and the track locks up AND the engine is not luging then the steering clutch could be out of adjustment or warn out. Go forward, then bury the blade, if both tracks spin then both clutches are OK, if not, that could be a bad steering clutch which is a bad thing.
Another test to check breaks and steering clutch function is when you go forward pull back both levers at the same time to see if the dozer stops and the engine does not lug down. Then release one lever at a time to make sure the steering clutch engages and the break releases. Most Dozers will go in a straight line, even if only one track is actualy being driven - the other track will just follow along.
Larry
