OS 50SX making a strange noise
Most likely the rear bearing.... shouldn't wear out that fast... even if not using after run oil like you should. Seeing several of you with the same complaint it may be an institutional problem with O.S.... maybe they did find a way to cut $10 off the price. If it was my engine I would put a quailty rear bearing into it(phenolic/plastic retainer cage) instead of a cheap metal caged one like the one that probably came with it.