I had an AC70 given to me 4 yrs ago (no idea how old it is) ... it would never start up again after a loss of power, and at times the propeller would stick. Bought a replacement motor for it ... but first I took it all apart, cleaned each piece and reassembled ... haven't had an issue since and still have a replacement motor ... Which is good, I've 5 AC70's running on 4 different tanks. Its the only one I've had issues with, but its also my oldest one.
As for when the propeller stalled ... I feel a little silly I guess .... never thought to use anything except my finger, as soon as I touched it ... it would start.