So my ring door bell (the original wired one) seems to either be faulty or malfunctioning. 

Sometimes it will show video and alerts, right now it's not. Doesn't seem like it's getting power. 

The original problem was that it wasn't ringing the chime pro we have inside. 

I put a multimeter across the two screws the wires went into and I see it's getting 6v by the looks.

Sometimes I can see it online in the app, again right now, no connection. 

The doorbell was installed by someone else a long time ago and I am trying to work out where they installed the transformer.

Any tips or tricks or advice appreciated.