[Vwdiesel] Vaccuum Pump Swap

[Libbybapa at wmconnect.com]

I just attempted to help an acquaintence swap her diaphragm vaccuum pump for 
a rotary style, as the diaphragm pump is not working.  Couldn't get the rotary 
one to seat properly.  Are they a direct swap?  I measured and the depth of 
the slot in the middle of the gear is a fair amount shallower than on the 
diaphragm version.  Was it bottoming out, or was I just not aligned properly?
Andrew