I appear to have a problem. When I am shooting the slide seems to not lock all the way forward after each shot and I need to manually push it forward. When the magazine is out it returns fine but when the magazine is in with or without bbs the slide will not return all the way on its own. Upon opening I saw that the nozzle in the bbu was not moving smoothly and was sticking. Has anyone had this problem or how would you recommend fixing it?