Hello! I recently acquired a transistorized ATO regulator (my first of this type) whose pendulum doesn't want to go. Its transistor is labeled TJN1, which looks like an early French germanium PNP transistor (source, source). Attached is a circuit diagram. I think it's roughly equivalent to this one, the closest I could find online - only with a PNP transistor, connected on the other side of the battery accordingly. I've effectively disconnected the coils and transistor for testing, and it seems the transistor is the culprit - both the drive and sense coils show resistance, and the transistor gives no reading between what appear to be the base and emitter (red wires in picture), using a multimeter in diode testing mode like so (I know just enough about electronics to be dangerous). Can anyone confirm whether I'm testing it properly, and/or suggest a possible source for a suitable (both electrically and aesthetically) replacement transistor to try? Thank you in advance!