Glock 18c Magazines feeding issue

i've gone through about 6 Umerex G18 mags, all of them with the same issue where the BB won't feed to the top. it looks like this small little plastic piece on them falls off which is responsible for correctly feeding the bbs. Does anyone have a fix to this? or maybe know a part i can order without dropping $50+ on new mags. The gun is super fun to shoot but the magazines have been a nightmare.