Perhaps so, especially since the radio has the same problem as well, right? The pot may need a lot of cleaning.
I know this is an ancient thread but I had the exact same problem on a wm-f5. No audio through the right channel on both headphone jacks and on radio and tape playback. When I opened it up, there was some minor corrosion damage by the volume pot. I checked continuity on the trace paths following the service manual schematic and shockingly, only one trace was actually severed. One real pain soldering a tiny section of wire in and now it has both channels again. This is just what worked in my specific case of course. Edit: I actually did not see that stray strand of exposed wire until I uploaded the picture! Took care of that. And yeah, my soldering skills are not good with small tight spaces.
