Was rebuilding a 4050-38 dc motor today ( it had presented with a major ground fault to the motor frame )
--on dissasembly, a motor brush unexpectedly fell out and onto the bench...hmm...looking closer, I find that all four brushes are still properly seated in their mounts...and upon inspecting the "extra" brush I find that it is it in new condition although a bit dirty and banged up here and there...the business end was even still flat ground instead of there being a curved area worn into it from rubbing against the commutator segments...
Apparently, Glentek in their grand wisdom had decided to generously provide me with a spare...just I would have appreciated if they hadn't of left it to roll around inside the motor ocassionally shorting the rotor etc and in general causing all kinds of intermittant and difficult to diagnose problems...
Oh well just when you think you've seen it all...