I’m having an intermittent cycling problem. after firing several rounds slide picks up shell and will not go in to full battery. Sometimes I can push the slide manually and it goes on in to battery but next time it’ll do the same thing I’ll take the magazine out and the rest of the shells are hanging up in the magazine , I have manually loaded magazines two or three times and slide the shells out manually and I can’t replicate the hanging up problem. Where do I start? Checking magazines or slide?