Using a slide hammer to pull an oil pump is a bit barbaric. This pump is the same as used on the VW air-cooled engines and oil pump pullers can be had for less than $10.00. 

https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=VW+oil+pump+puller

Using the slide hammer can also pull the pump out at angle messing up the bore in the case. 

I have not seen the lower gear post move on its own but I have seen it hammered in when a hammer is used to install it. This fit is critical as it is the fit that seals both the inlet and outlet of the pump. Unless this engine was a rebuild someone may have changed the pump already to try to fix the low oil pressure problem. While I have seen oil pumps installed with the wrong gasket on the cover reducing the effectiveness I have not seen a pump actually wear out unless something got into it. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Dave Bohannan
Sent: Tuesday, August 9, 2016 10:15 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Oil Pump Questions - Bottom "gear post" creep?

Through an odd twist of providence…I now have 3, 30mm pumps waiting to go in…

So removal of the old pump was a snap with the slide hammer from Advance (free rental, came with a hook puller…)

Once I got it out, however, I was taken aback…the bottom stud that the gear rides on seems to be creeping BACKWARDs- about  3-4 mm…so much so, that it may have ground into the shaft behind it… As evidenced by a small shiny spot on the back of the stud, and a shiny ring all around that shaft…

The stud isn’t “loose” as far a me pushing by hand…but maybe once the engine got hot it decided to creep? I just do not know...

Comments? 

Thanks in advance…

Dave