The clock in my 81 300D was working fine and now it's doing some wired stuff. My clock stops working at some point in the night so I reset it in the morning and then it seams to work fine through out the day but when I get in it the next morning it's apparent that it stopped again throughout the night. I set it again and again, it works fine throughout the day.

I've seen these clocks stopping working all together before but mine now works throughout the day and stops at night. Is there something that got disconnected that keeps the battery backed up or is my clock just on its way out?