My bmw has recently decided it doesnt like going into reverse. It goes in fine when its cold but while its warming up it doesnt go in until the car is completly warmed up and it doesnt go in to reverse while the car is cooling down either. The gearbox has done 130,000ks and the fluid was changed about 3000ks ago. Any ideas on what ths could be?? The filter hasnt been changed either. Cheers