Replace the chain and crank sprocket-- they're worn.
The camshaft tip is machined from the same casting that the camshaft is. The cam sprocket is a good press fit with a key to the camshaft, and (in the unlikely event) it was loose you'd see all manner of destruction around the keyway.
'73 R60/5 Toaster
Luddite. Not just a philosophy, a way of life...