Hi y'all! I just bought a L1A1 "sporter" with an Imbel receiver (thanks to the advice I found here). HOW do I get that thumbhole stock off it. I bought another stock kit, but the grip doesnt have a place for that weird hinge thingy from the trigger. I got the screw out of the buttstock (and the springs) and the screw out of the hinge thingy, but the stock won't pull off. What am I missing here? and what other things will I need to install the new one? thanks in advance.