kj works glock 23 slide problem

i recently bought a kj works glock 23 and whenever i put an empty mag in the gun and rack the slide or shot the mag empty. the slide does not lock back. it use to but out of no where it stopped. also the guide that pushs bbs to the top of the mag is extremly hard to pull down, i even put some oil but still it is a pain, i need to use a tool of some sort. please help