McCullock 436 chainsaw clutch?

either the drum bearing has seized or broken up,or the clutch spring has broken, you first need to remove the clutch, once off check the condition of the spring ( if you can pull the shoes apart by hand you will need to replace the spring ) if the cluth is ok, pull the drum away from the crankshaft, check the bearing condition, this component is only available as a complete drum and bearing.

Husqvarna man
November 2009