Good habbit on Vintage MB's.... torque and tighten various nuts'n bolts like the fuel pump, oil filter bracket and carburetor mounts. Also include sump pan bolts on tranny and engine if you're underneath the car. Typical torque oughta be about 27-29 lbs.... no more.

I'll betcha that tightening the fuel pump w/out replacing the gasket will seal the leak..... not alot of crankcase pressure, you understand.