I know nout about these dozers but have often cleaned out ag tractor transmissions by filling with cheap or s/h oil ,run a little at first ,drain warm/hot (dont get burned) into a barrel ,leave over night or longer in the barrel ,tilted away from barrel pump side ,check screens , magnets (change filters pend )pump the same oil back in ,keep the pump well up from the barrel bottom and pump the same oil back in ,leaving behind the last few gallons ,topping up with other oil . Work a bit longer next time and repeat