I have a sk200 mark 4 that tracks stopped working. Both tracks stopped working at the same time. Other functions such as boom, stick, bucket curl still work. Machine will track forward if I am swinging but as soon as I stop swing machine will stop tracking. Machine will not track backwards when swinging. Machine serial number yqu4046. The kpss switch does nothing but I never use it so I don't know if it has worked in the recent past. Machine LCD dash is gone and has been replaced with gauges but machine has ran that way for years.
the kpss knob should be in h or s. d is independent travel. if you lift the track off the ground does it turn then? what happens if you stall boom or arm do the tracks move then or is it only swing.
If I pick up one track and try to spin it the track will spin if I push one tracking pedal forward and one backwards at the same time. It will not work by just pushing one pedal. Matching will not move if I stall boom or stick and try to move.
The seals in the swivel/centre joint could be cactus, it's the only common part to both tracks in the plumbing.
Are you able to connect gauges to the pumps? if so I would check your pressure with the track stalled and compare it to another function. if pressure tests ok I would check the case drain return from each motor, it's possible that with this old of machine the motors are bypassing too much oil and have no power. if the case drain is not excessive I would move on to your load sense pressures back to the pump while traveling. they should drop to zero when tracking and have about 450 in neutral if I remember right.