[Vwdiesel] VW injection pump head seal replacement

[Caleb Van Dyke]

I am attempting to put a new O-ring seal between the pump and head, but I have a few questions:
 
The procedure that I am using (someone referred me to it from this site) says I need to
Install a short spacer and retighten the bolt down. Loosen torx bolts a small amount (1/4 turn each) and tighten the center bolt down a similar amount. Gradually work back and forth between the torx bolts and the center bolt loosening the torx a little, tightening the center one a little. When flush, the bolts are inserted clost to a 1/2" so there should be plenty of threads still inserted into the pump to keep the bolts from falling out. 

Why do I have to install a short spacer? I do not see how putting a spacer and then tightening the bolt down as I loosen the torx screws will accomplish anything. I would think the bolt would just tighten down on the spacer and then stop, not keep getting looser as I loosen the other bolts. 
 
Also, there is a procedure that I found on the internet for rebuilding TDI pumps made between 1996-2003 that looks very similar, but doesn't mention anything about this center timing bolt. 
 
 
Any help would be greatly appreciated.
 
Caleb