Smaller spring? It sounds like your referring to the BOV but have to assume your referring to your wastegate.. Confused eather way though.. The screw part is good info though.. My ---- is still fluttering even with it almost all the way out..

 

I am using a ebay greddy RS and I have to tighten it half the way for it to hold boost then again I run 23psi.
the downside is if you are a ricer and want to tell everyone that you are boosted it won't go off at low boost, but when if it blow off its a wicked sound.

 

are you sure it wasnt holding boost. a bov has pressure comming from the bottom, and the top, but the spings gives added tension to the top so it should hold no matter what, even if the screw is out all the way you should hold boost no matter what.

 

it will hold boost, but not at 23 psi on a sc61, even when I was using a blitz it would fall off if I had the spring too loose, say I set my boost to be 20psi at wot it will not maintain it if the setting is too loose it would fall off to 16psi the I tighten the spring and it will hold 20 all the way till I let off.

 

You said you changed the vac line to the bov, make sure its not colapsing and sealing itself shut when in vac.

 

The problem isnt holding boost.. Its getting the BOV to open..
Well I changed it to a bigger and thicker line so I dont see that happening but I will definately check for that.