i have removed gearbox on my bosch gbh4 dfe after drill slowed down and stopped. the gearbox was hot but motor cool with no smell of burning out. i regreased gears reassembled, motor ran fine but could not change mode. the pin on selector knob is very difficult to engage in spring as you push gears back into front housing. i tried prising knob off alltogether but it wouldnt budge

steve adams, July 2011