The big bolt is the tensioner.
Unfortunately i haven't got any pics of it stripped down.
When you do remove the cover, be careful not to damage the headgasket, and yes it does come out that far!!!
I'm not sure what you will need to take off, the coil, the tensioner, probably the inlet manifold and cam cover as well.
More than likely it is a broken guide rail, they are plastic sh!t, once stripped down it is easy to replace, i done mine when doing the head gasket.
I would also recommend replacing the tensioner bolt as well, the early type are hydraulic only, and can fail.
I have still got the bentley mk3 manual, let me know if you need any more help
