Old Yamaha 100 mixer (left side not working)

[MagnumPI]

HI Guys, I got this old Yamaha 100 mixer from a friend. It was used in an indie club in L.A. in the 90's and mixed bands like Nirvana, Beck, Sonic Youth, Elliot Smith, etc, when they came though this little club. I have it now and was thinking about fixing it up. The problem is when I plug my headphones in I only get the right channel working. It seems the left side it totally dead. Any ideas where I should look to start fixin it up?
Thanks

 

[sweetbeats]

Do both meters deflect with stereo program material? Do both left and right line outputs work?

I'd check those things first to get a sense of how extensive the failure is.

If the L meter deflects and bpth L and R outputs work, then I'd be looking at the wiring to the headphone jack and then keep going upstream through the headphone amp...inject some tone into a channel and pan it center, and take your meter and physically follow the wiring and/or traces back from the headphone jack until you find your tone. Panning the signal center will allow you to compare what you measure on the R channel at points along the way and compare to the L channel.