Ice Maker Issue

Last week, my ice maker stopped making ice. I realized that a large ice dam had built up on the back of the freezer and had clogged the water supply hose. I removed all the ice and reinstalled the ice maker. The ice maker is making ice again. But now, the arm that turns off the ice maker stays stuck in the up position after the maker ejects a load of ice. The gear inside inside the ice maker cover is turning. But the arm rises when maker ejects the ice and stays there. Any ideas what could be causing this? I took the icemaker out over night (in case something inside had frozen when I first took it out and reinstalled), but that didn’t do anything. The fridge is about 12 years old, but I replaced the ice maker 2 years ago. Thanks.