[Texasrocker]

Hello, to open-up the old volume control is easy. Carefully pry-up all the front control housing tabs, flatten with small pliers, and remove front shaft & wiper assembly from the housing. Then, you can visually inspect the carbon trace for broken intermittent operation. If you dont see any visual probs, blow off the dust & debris, and relube the wiper assembly with a shot or 2 of WD-40. Rotate the moving parts in the wiper till shaft is also lubed and rotating easily as well. Make sure the on-off switch section is properly aligned and relubed as well. Wipe off excess lubricant carefully, then reassemble control and bend orig mount tabs back to orig secure positions.
I haved saved many vintage controls in the past using that method! The old-timers used to use a #2 lead writing pencil to fill in worn carbon traces on the wiper. Ive never had much luck trying that idea as most vintage controls are now too worn.
For vintage radio controls replacements if needed, http://www.RadioDaze.com has a nice selection of both audio-taper, & linear taper modern replacements with new on-off switches assemblies also in various ohms ratings with long round 1/4"shafts. The shafts can be modified to your needs by using a dremmel tool to grind the shaft on one side, and/or, cut the shaft off your old control and add it to the new control using a 1/4" to 1/4" shaft-coupling which they sell also. Check their "components" section of their website. Best of luck on your restoration!