What cause gearbox teeth to chip off on mini? I’ve replaced them heaps of times in last few races, I’m talking once every 2-4 meeting. Wasn’t like this before. I’ve checked pinion and diff but no damage at all. Just middle gears and I can’t see any rock or any thing like that inside. I’ve tried –lube gears – no lube –silicon splay all same result. I use gear diff build as per instruction with AW grease inside (not tight at all)