Vending timer not advancing

[Sam Christy]

Any insights on why the clock on our vending machine (Ams Sensit 3 model 35 or 39) is not advancing? I am the robotics and engineering teacher at our high school. The person who manages our vending equipment asked if my students could help fix one of the machines. I guess qualified vending maintenance workers are hard to find. The vending machine had been in storage for many years before she bought it. She thought the clock stopped working af few months ago, but one of my students noticed that the date it stopped working was the first day of school and we now suspect that it has not worked since she purchased the machine. 

All the electronics inside look to be in very good shape and there were no obvious lose or disconnected wires. We suspect that the coin cell battery is used to back up the clock when the machine is unplugged. Given that it was in storage for many years, it is likely that this battery needs to be replaced, but that should only account for it losing time when unplugged, as opposed to not advancing. 

Any suggestions would be greatly appreciated.

Sam

[AZVendor]

Probably a bad timekeeper chip on the logic board. You can get a replacement from Mouser.com.

[Sam Christy]

We have used a lot of time keeping ICs in our engineering projects and never had one fail without a good reason, but might be possible.