I got a pair of micarta scales for my stretch Hap40. I tried installing them, and I think I wrote here about some of the issues I had. I got it back together but it has no springiness to the lock and it rocks back and forth around the pivot. I inserted the long flat part of the lock bar into the slot at the top of the backspacer, should I have put the short part of the spring into that slot? I tried doing that before but was having lots of trouble getting it back together.
Please tell me you have got the spring oriented in the right direction. I will assume you do.
Something to keep in mind is that a back lock lockbar is just a giant lever. So with constant spring tension the closer the spring contact spot is to the center pivot, the easier (less springy) the action on the lock bar will be.
Basically make sure you have got that spring bar jammed all the way back into the spacer if you want more springiness. You may have a piece of lint or something that got in the backspacer during disassembly, not letting the spring fully seat into it. This would move the contact area towards the pivot and give the impression of reduced spring tension.