The adjustment collar on one of my Slims (Code H-2) would not move beyond the 4 setting. It moved freely from 1 to 4, but would not budge beyond. I found a few threads that addressed the problem and tried lots of things - hot water soak, Scrubbing Bubbles Soak (5 overnights), mineral oil soak, etc. One thread suggested pushing in the spring above the collar with the end of a paper clip. I did that and, lo and behold, the knob turns freely from 1 to 9 and clicks at each stop. That's the good news. Bad news is that the collar has come down from the neck and will not go back up. It also appears that the adjustment bars do not move as the collar turns. I would love to hear suggestions if anyone has any. I posted a picture below. The razor on the left is the one with the problem. The one on the right is another that works fine (Code H-3). The doors on the left razor are slightly open, that is not an issue.