If the marker worked when it was stock, and now doesn't, replace the stock parts. If it begins working again, obviously the problem is the aftermarket parts. Other things to look for are the battery wires getting in the way, make sure nothing is impeding the movement of the pin, make sure the batteries are FRESH. If you bought the batteries at your local 7Eleven, they are most likely dead. Does the marker work in semi auto mode? If you have been messing around with the settings, reboot it to stock settings and see if that fixes it.