Komatsu D20 A steering clutch problem.

Komatsu D20 A, we replaced main clutch recently along with steering clutches and all works OK until the dozer has been worked for 10 or 15 minutes then we lose the soft steering both sides. Replace the pump with new pump, no change. Let the tractor cool and steering works OK again. Pressure tested Valve body just before slave cylinders at 100 PSI when cold. Steering valve body under tractor has been cleaned and inspected. All out of Ideas at this point. have we missed something? Thanks.

check your brake band im sure you know where the little plate is for both sides, crank it in till you just start feeling some resistance then back off 1 1/2 turns ,,, when you pull back on the lever the first half that arm with the wheel on it presses in on that chrome button this engauges the steering soilnoid to push on the arm.. now the last part when you pull back on the lever this starts pulling on the brake band this is what starts locking the drum down so you can turn quicker,,, you can fine tune this to your liking by turning in or out on the brake band adjustment..... now if this does not rememdy your problem then your really not going to like my next sugestion at all so pray pray pray that the adjustment fixes your issue let me know