Far as output voltage its 13.8 volts at least on the original. Had an elderly lady call me that the same pro 197 wouldnt work a few days ago. The walwart was only putting out .5 volts.
Granted not everyone will go this far, but it worked here.
Luckily my brother had some walwarts from old devices he had. One was 13.2 volts output, an old RS house brand Archer.
I clipped the mostly no one ever uses the plug for the wiring harness for a vehicle, spliced in place the plug that didnt fit from the archer walwart. Twisted the wires together, put solder on those, electrical tape around both wires and put a piece of heat shrink tubing to finish it and it works, One happy lady she was!