Well, you have painfully$$$ learned what a bad bearing feels and sounds like when it's gone too long. But the good news is, 90% of the time, if you pay attention you can catch it before any major harm is done....next time.
Signs of a bearing going out: A gritty feel and sound when the prop is turned while pulling forward, A whining or turbine like sound while in flight, Power loss with correct needle setting, Suddenly glow plugs are going out quickly and its not lean(eminent engine damage).
Cheap fix: stainless & plastic cages.[sm=thumbup.gif]
http://www.rc-bearings.com/catalog/p...roducts_id=715