Use a metal chisel/drift and gently tap it down, it'll need to rotate clockwise slightly as it goes in... But be warned, you might've slightly chewed the drive gear on the crank...
Ill a e a look and let you know. If it is that would be a right bonus. How do I go about cleaning out all the crap in the engine? Is it just a case of changing the oil. Running it up, changing the oil and so on or is there a better way without splitting the case?
Engine flush is a good a tool as any... but see how you get on with that dizzy drive shaft first, as you might need to split the case to replace the drive ring on the crank...
