PROBLEM: The icemaker is overflowing into the ice bucket below, locking up the auger.

HISTORY: I have had this frig since 1986 and it still works well. I have successfully replaced the icemaker and the water valve several times. I have hard water with no water softener so I think it is hard on the valve and icemaker. I replaced the icemaker again just a few months ago and it has been working fine. After awhile the icemaker began overflowing into the bucket below. It seems to be gradually getting worse.

Perhaps I could fix it by replacing the valve again, but I have noticed that the icemaker has what appears to be 2 nylon adjustment screws on the front and one small one on the right side at the front. I thought maybe one or more of them can be used to adjust the time that the valve stays open, so that I won't have to replace the valve right now. Can you help?