Ducklakeview said:
Happens a lot when they are stored - Basically the sponge the motor is wrapped in will be wet, when it's put away the corrosion will set in on the lower bearing and commutator. The first time it is then operated it will usually work, as the area under the brushes on the commutator will be relatively clean, so away it goes and then comes to rest with the brushes on a corroded section et voila, it won't work. After driving, it may then work intermittently due to the vibration jiggling things around, but the only sure fire way to cure it 100% is via removal, refurb the motor and relocate it.
Mike
What Mike and all above have said.
It's only a matter of time now and it will die eventually unless you can get it out of the water filled flask it's sitting in.
There are members in that will relocate neatly it into the boot for you, if you wish :-
DucklakeView - St Helens (Wirral)
Number5 - Bristol
Bowser123 - Hampshire
Durham Dave - Cumbria
DietCokeMan - Bucks