Time for a new one. I have some GPS' that are over 20 years old - remember the original Garmin 45s? Most of them have some sort of malfunction around five years. They're cheaper now and the screens are larger, buy a new one.
On your computer, see if your current GPS is new enough to work with Garmin Express. This allows your saved locations to be transferred to your new GPS very easily. If you have any problem in doing it, call Garmin and they'll walk you through it while on the phone.
Another feature of Garmin Express is keeping the saved locations the same in all of your GPS' that are new enough to use this feature. I have three GPS' that I'm actively using. One in the MH, one in the toad and one that's a back-up. When I get home from trips, I hook them up (one at a time) and Express will transfer or add locations from one GPS to the others so that all saved locations are in each GPS.
Bill