It might be something unforeseen in the wiring of the doorbell itself. Can you upload a picture of the doorbell terminals and mark which terminals you are hooking the Pro Power kit to?

Here is a picture. The two ends of the power kit are attached to Front and Trans. 

That definitely looks right. And since the device is in parallel it doesn't matter which end goes on which terminal. So that's out the window. But what's odd is, you say the everything works without the kit when you ring the doorbell. From what I saw on my system, without the Pro Power Kit, the moment the doorbell was pushed on the Ring Pro 2 the solenoid would be anemic and would take up to ten seconds to complete the ring cycle. For you it works without it. So here's my theory, and please take it with a grain of salt since I haven't done this type of works since the late 80s. Maybe your transformer is providing more current than mine does. And that might actually explain the hum. The solenoid is just at the state of trying to engage due to the exact voltage/current condition starting to be met with your Ring Pro 2 in the circuit. Wish I could provide more help but you've reached my limit of experience with Ring hardware.

Hi @jat1228. The Pro Power Kit does need to be installed in your chime when [installing your Pro 2](https://support.ring.com/hc/en-us/articles/360054675132-Video-Doorbell-Pro-2-Installation-guide-), and based on your picture, it looks correctly installed. Also, you took the right step by checking your Doorbell's chime setting to make sure it was set to mechanical. You also want to make sure your chime is compatible with the Pro 2 by using this Help Center [page](https://support.ring.com/hc/en-us/articles/360059789591-Ring-Video-Doorbell-Pro-2-Chime-Kit-Compatibility-List). If it is compatible, I recommend reaching out to our [support team](https://support.ring.com/hc/en-gb/articles/213608406#store-opening-hours) once more to further investigate your concern.

Hi I am having the exact same problem. Did you find a solution?