Annoying ticking sound while driving.
A bit tricky to do with a manual but if you can safely load up the engine with the hood up you might be able to see the engine rock.
Also look at the blade tips and the inside of the shroud for signs of contact.
Another thought is if the thrust bearing is going maybe the crank is moving and hitting something.
But as my dad always said...
KISS (keep it simple stupid)
look for the low hanging fruit first