I just got a Walkera BL motor (with pinion) from Highvolt Heli but the pinion is the wrong size so the teeth don't mesh with the main gear. This supposed to be a direct fit (upgrade) and I didn't find out till I had already pressed the gear on and tried to mount it. Anyone have an idea what pinion I need and where I can get it? The shaft size is a 2.3 mm.