Is there any trick to replaceing the odometer gear that always breaks? I've done it twice now using good gears from PYP cars and both times they've broken before I've gotten half way down the street! The odometer never moves and the last time I could even hear the crunch as the tooth snapped off. It's a fair amount of work as some of you know and I REALLY only want to do it one more time. Everthing seems loose an moving freely before I put it back together. Thanks....