[Radioroslyn]

Yes you are missing the 7Y4, it's the low voltage rectifier. The connector has been changed the except a pl-259 connector (very common connector).  Most vtvm would have a length of shielded cable or coax  with a 1 meg resistor in series with the center conductor going to the tip of the probe. The black connector takes a banana type or pin type connector. The banana is a bit fatter, hard to tell from the pic.
RS used to carry these parts and still may I haven't been to one in a while.
The HV probe is going to take a little guess wurk. Most have a resistors inside the drop the voltage down before it gets to the meter. Your has a large resistor connected to the connector on the backside. When you get it working try measuring a relatively small voltage with it without any resistance in series and see what kind of reading you get. HV probes are big and look like a turkey baster with wires.