On Sun, 7 Sep 2008 15:53:27 -0700 (PDT), Peter C wrote:

I now find that on the chain drive side the top pulley can be turned
by hand when the engine is not running, also when the problem shows
upon trying to cut the lawn the chain is not revolving.,

Maybe the woodruff key has sheared or dropped out? If it has a woodruff
key that is.

http://en.wikipedia.org/wiki/Woodruff_key

Qualcast have an website but it is not accessable if you don't have flash.
The online manuals are for more recent models and I haven't found a proper
service manual anyway but they have contact information.

--
Cheers
Dave.