Benz Refs stripped screw hole

Using a larger bolt is a recipe for disaster.
Try wrapping some plumbers tape over the bolt - this may be enough to get some purchase on the thread.
Alternately, why not send the cartridge to someone like Soundsmith to effect a proper repair. Should not be a costly repair.   

I did not know it could be repaired.  Thanks.

I would explore a longer screw but make sure the thread pattern is the same. A 1/4 inch longer will probably do it.

IIRC, the Benz is a wood body.......

(1)   Make a paste w/ some sawdust + wood glue
(2)   fill in the stripped hole
(3)   when it dries, drill a hole with drill bit that is SLIGHTLY SMALLER DIAMETER THAN SCREW!!

The hole will kindof self-tap when you insert screw for first time.   Should be nice and tight now.

Benz has a wooden shell but the chassis is threaded aluminium.
Threads are 2.5 mm so perhaps if you try 2.6mm screws might help ?