Yeah, some clones aren't wired well. Its like the lottery except you don't want to win...
This page will be loads of help to you as far as connectors goes.
http://www.airsoftcanada.com/showthread.php?t=26918
The gist if the article is that you should solder where ever you can and use deans connectors on anything you will me changing often.
Look at your trigger contacts. Do they look burned out? Unless you have been using a higher voltage than an 8.4v mini, the odds of your contacts being bad is pretty rare.
I think i got it all right, but if I am wrong please correct me so that we can both learn.
Best of luck, I hear its a pain to close the jg mech boxes.