For those out there who have wire-wound volume control pots that are open (as happens in early models like the Model 20, 41, etc where volume is controlled by varying B+ to the screens of the RF amps) you can fix these wire-wound pots using rear-window defogger conductive repair solution. Just paint some on the inside of the potentiometer winding over the break in the wire. The resistance decreases very slightly (usually about 4k) but this doesn’t seem to matter…works for me.
What I use is “Loctite Quick Grid Rear Window Defogger Repair Kit” part no. 15067. Here in Canada I get it at Canadian Tire but I suppose Walmart or any other automotive supply or parts stores will carry it.
From Lee Barker – Exerpted from a message thread in the Antique Radio Forum – Electrical/Mechanical Restoration.