You should remove the belt for better access. Also detatch the top mount of the tensioner damper (shock absorber). This will allow you to pivot the tensioner arm and puller out of the way of the pump. Good time to check for smooth click free pivoting of the tensioner arm and smooth quiet spinning of the tensioner pulley.

I read that if the driving cam is pitted or has wear marks, it should be replaced. I don't recall if the driving cam is part of the timer and if so does the timer have to come off to replace the driving cam.

It's best to loosen the pump bolts a little at a time since the pump lever is pushing against the driving cam, pushing the pump forward. There might be a sweet spot where the lever is against a low in the driving cam but I don't know how that relates to a crank pulley position.

Sixto
93 300SD