

I have this Lanshire XL7 electric clock when I plug it in the clock makes a humming noise and thats about it, I can see the gears jumping around a bit but nothing constantly going round as it should .
but when i remove the backing plate turn on the power and shazzam of it goes running like it should gears are turning life is grate ,but as i start to put the back on it while its running i can feal the magnetic field have a hart problem and when its fully mated together its stops running actually it sort jumps back and forth trying to run like its jumping from postive to negative ,
any idea as to what would cause this thanks Brett.