Troubleshooting Additional Coins not being Recognized

[Protel8000]

Hey everyone, I hope this is the right board to post this in. If not, mods, please feel free to move or have me repost in the correct board.

I have a phone (I believe it's a WE) that was from Verizon, upgraded with an 8000 Protel board.

The phone recognizes the initial coin deposit to connect the call. However, when it's time to deposit additional coins for the call to continue, the phone doesn't seem to recognize that additional coins are inserted. If it's a quarter to continue the call, no matter how quickly I deposit a quarter, the phone doesn't seem to recognize that it's been inserted and disconnects the call. The same quarter will work just fine for the initial coin deposit to start a call, and I've tried multiple coins. Also, the phone passes the coin recognition test in the diagnostic mode.

Any ideas on what I should check? Could it be a software setting? Here are some pictures of the exterior, if it helps to confirm the identification of the model. I can open it up and get pictures of the inside components if that would be useful. Thanks!

[Protel8000]

I forgot to follow up on this post. After talking with payphone installer via e-mail, things started working properly again. Not sure what the actual cause was, but I haven't had any further issues!