I have had the dreaded cog issue and replaced it with another nylon one, it ran fine for 5 mins and then the problem returned.
I had greased it and there doesn't appear to be any end float on the bearings/ roller brushes etc, the plastic ends where the bush sits are not worn and all parts move freely. I have seen replacement shafts available with a metal cog, so what's the general opinion on these?
Surely the reason for plastic is that its sacrificial, so should anything jam up then the motor/ other parts aren't damaged.
So, should I look for a fault somewhere else or just push ahead and buy the metal gear?