Hi @dpmartin66! If the Pro is operating just fine for some time, this is a great sign that your power supply is adequate. You mentioned wiring being old, which certainly can effect the flow of power to your Doorbell Pro. Variables such as a lengthy wire run (100 ft plus), old/ corroded wires, or even thin or spliced cat5 wiring can cause resistance in voltage.
If you’ve checked these variables and the Pro is still not powering up as intended, our support team can certainly assist further. If needed, the Protect Plus plan does offer an extended warranty if subscribed prior to initial warranty expiring. Please give our support team a call at one of the numbers available here. We’re taking additional steps to protect our team and help reduce the spread of COVID-19, so this has resulted in longer than normal wait times. If you are outside of the US, please read our response to COVID-19 here to see how to contact support.