ics m4 advice

[chicken]

So I have an ics m4 that the hop up is busted. I did some research to see if any other hop up's would work. Some say that the king arms unit would work. So I when for the challenge and have been chasing my tail ever since. I can get it to fire yet it seems to jam up after a couple of shots. I have attemped to change buckings and nubs to see if that would help. now I am stumped. If anyone has done this mod and has suggestions please help. Also if anyone else has suggestion i am up for it. thank you for your time and suggestions.