Hi Folks, I bought a lightly used MkIIV a couple years ago and it's been great. The only issue I have is that with a couple of the mags, the slide will not lock on an empty magazine. After playing with the ones that are failing, I see that the issue seems to be that the "button" on the mag follower is skipping over the slide catch instead of pushing it up. If I slide the mags in gingerly I can get them to lock the slide back, but if I slap them in they will jump over the slide catch. I only have this issue with 2 of the mags which are older, the other 3 seem to be fine. Does anyone have any tips on how to correct this? Mags are expensive and I would hate to just stop using them. I looked for some replacement springs for the follower but only saw the large mag springs. Thanks in advance.