Remove the hex socket head screw holding the clamp.

Use a special 31-spline? socket to remove the delivery valve cover.

There is a sring under the cover.

You'll probably need a new o-ring for the delivery valve cover.

There is a special tightening procedure for the the delivery valve covers of a 603.961. I suspect there is a similarly special prodecure for your 602.xxx.

HOWEVER, I've heard that the drip method of timing is not the best or even advisable for the 'newer' Diesels. Much better to use an A-B light. It drives techs nuts but DIYers find it acceptable to use the IP locking tool as a guide to setting timing.

Sixto
91 300SE
87 300SDL
83 300SD