Suspected worn cam lobe, won't know for definite until it is removed for inspection

Cracked flex plate maybe, remove cover plate at the base of the engine sump and you can then see the plate, just trying to remember if there is a rubber bung that also allows you to see the flex plate ?

I wanted to check the oil pressure to rule out a low pressure problem while investigating a tapping noise, unfortunately the method to connect a gauge as described in the workshop manual is impossible on the Thor engine due to ancilliaries and...