Hydroboost leak HELP

[67rstbkt]

Having Hydroboost woes I'm hoping someone can help with or at least confirm I'm doing things right.

I've had a used Astro Van unit on my Firebird for well over a year and it recently started leaking. Looks to have been from the seal in the piston. Rather than try to fix it, I ordered a rebuilt unit and put that in last night. That one is leaking from the plug at the front (with the slotted fastener).

Could I have messed something up or do I just have bad luck?

The power steering pump is a stock style GM that was modified for Hydroboost and the quick ratio box by Lee Steering. I'm about to pull the trigger on the bolt in unit from CPP since Summit has one in stock, but I want to make sure I didn't miss anything. Anyone know what that plug is for anyways?

****EDIT****

Looking closer at that plug, there was a pipe plug in there (allen) - I pulled off the little rubber cover and that thing was loose. I have no idea what the plug is supposed to do, but I tightened it up and took it for a test drive. Car still stops - I'll take it for a little further and see how it goes. What a joke of a rebuilt unit if that's what it is.