simpson sirocco 500 tumble dryer?

It is a plastic belt running over a plastic pulley. If belt is still tight to put back over the two pulleys then it may be sticking to the pulley when not being used & when motor starts it causes it to jump slightly. Put belt on & start machine with cover off belt. Spray some silicone spray on to belt while it is running. This will help it to not stick to the pulley. If belt is loose to put over the pulleys then replace it with a new one. There is no adjustment to tension the belt.

Lincoln Appliance NZ
April 2009