I have just had the same problem, but found out that i wasn't pulling the tensioner wheel in the right direction, so there wasn't enough tension on the belt to spin more than a few garments at once and the drum would stop rotating.
The tensioner wheel has to be pulled over to the right hand side of the motor, and then the belt should run over the left side of the tensioner wheel and over the motor drive. It's a bit tricky and will be easier with some help from somebody else to either pull the tensioner for you, or slide the belt.
M. Roberts., November 2006
