Hickok 534 Tube Tester broken wires

I just acquired a Hickok 534 tube tester which seemed in good condition; however, I found a couple of broken wires and cannot get the line adjustment.
Tubes are good, but I noticed that there might have been some service performed in the past around the P4 pushbutton.
I cannot reconcile the wiring with the schematic diagram; in fact, according to the schematic, one end of R6 is connected to R3 and to contact #7 of P4; this is confirmed on my set too.
The other end of R9 however, according to the schematic is connected to contact #5 of P3, contact #6 of P2 and then to the Micromho switch.
The wiring that I had in my unit instead connects that end to one end of the potentiometer R4-R5; from some of the pictures (not great) I was able to retrieve from the internet, it appears wired in the same way. From the schematics, neither end of R4-R5 is connected in any way to R9.
As I said, I ran into this puzzle because I found a broken connection on the wire between contact #7 of P4 and R3.
Of course, any input or info would be extremely appreciated!
Thanks!
Eugene