My 1995 Volvo 940 GL, mileage 250,000km. Problem is after the gear shift lever moved to Driving (D), the gear is not engaged and car won't move. I have to either wait for 10-15 mins for the gear to finally engaged or i need to ram the engine moderately before the gear engaged, with sudden jerk. Once moving, no more problem. I wont put to N at traffic lights fearing that it will not engage again. Reverse is OK. Transmission fluid is OK. Why? Need total change of gearbox? very costly. Appreciate advise.