domnt do anyting, first try to tap in a see if it works, otherwise you might be chasing your tail!...first see if it works the you have to decide to get rid of the am or fm, other wide it will crackle when you play!...its an easy hack, just see if it works for with aligator clips attached to the am or fm leads
hTwo holes (sorry, but necessary). One for switch, one for jack. Find wire that runs from tuner section to on/off volume pot. Cut that wire and connect the tuner side of that wire to one side of a spdt on/on switch. Connect the positive lead from jack to other side of switch. Middle post of switch connect to the remaining tuner section lead toward on/off volume. Remember to connect jack negative to radio ground.
Now you have a unit that still operates as a radio, and with flick of switch, its a guitar amp.
Winnipeg? Ugh. Lol. I can get a couple US am stations in New York. My thread on the 64 Phillips has a diagram showing what had described.
Having a "flying" cord... clamped to the chassis (hole drilled?) with a female 1/4" phono plug available for your guitar hanging in the rear cabinet, will give you the ease of "plug'in up", the switch part could be had with a 3rd contact in the female 1/4" phono plug. The only issue is that this 3rd contact is available with a logic state of "grounded" with no plug inserted, and un-grounded with the male inserted. That tells me that a relay will be doing the "mode switch" switching. Another possibility that I would prefer is to install another rotary switch with an additional position, and then chassis mount the female 1/4" phono plug with of course coax, that is IF you don't already have an AUX input. antiqueradio.com is a valuable resource, excellent choice.
The radio should receive an alignment at some point, so you can enjoy it as it should be. I would not plug it in until you have the newer 3 wire grounding power cord & the power supply caps replaced. Oh, yes, you'll need a good bench technician as well. Good luck, I'm sure it will sound great, even better some "low Fi" can't hurt as well. Even some bias work on the pre-amp section with a 2 pole rotary switch to work that 40"s tone up a little....thats what I specialize in!
Radio museum is a great resource for info. The actual voltage requirement is not included, unfortunately. Those used dry cells. But an alkaline alternative will do fine if you can match voltages. I believe the "alignment" has to do with the phase inverting diodes that affect the radio signal to a more usable wave before it passes through the pre amp stage of the circuit.
There ya go, 4 AA batteries, 1.5v each gives the 6v power source, excellent