Enfield America MP 9

I recently came across an Enfield MP9 completely apart, buried in a garage for years. A friend and I cleaned it up, oiled it up and began to put it back together. I have very limited knowledge of firearms, so any information is helpful and please correct me if I use a term wrong.

The main problems we're having involve the BCG. one issue we've encountered is that when a magazine is loaded, it will not cock, the BGC wont budge. There are a couple more problems all involving the BCG.

My question is: does anyone have, know where I could find or could point me in the direction of some form of assembly instructions for this mp9 or a similar model, that would aid me in figuring these problems out. Im also open to educational materials about this type of device, Ive looked long and hard across the web and I cant come up with anymore than the history of it, and similar airsoft toy remakes of it.
Identical to : http://www.gunbroker.com/Auction/ViewItem.aspx?Item=192106614#PIC