Thanks Grumpy

I found the rattle, its in the starter clutch. I'm assuming a rattling starter clutch might make it hard to turn the motor?

And this exploration has probably gone further than it needed. I'm probably gonna pull the whole thing apart now so I know where everything belongs, not confident I'll get it back together again but I'll have fun trying smile . The mower is a throwaway, so no great loss.

I'll have more questions I'm sure as I dive in further. cheers