Left channel not working (jumper fix not working)

[smodtactical]

So my left channel stopped working after several months of perfect operation of my stock crack (no speedball). I noticed once of the LEDs was not lighting (the one attached to A8). I tried to reflow my joints at a8 and the center but that didn't work. My voltage checks absolutely matched the manual.

I took out the LED that was not lighting and did the jumper between A3 and A8... still the left channel doesn't work. Any ideas?

[smodtactical]

I just changed the 12au7 to another I had and now it seems to be working ? Weird. I'll keep an eye on it, thanks.

[Paul Birkeland]

 I would be willing to bet that the wire between A4 and A5 isn't well connected. 

Having one LED light up and one not light up is not an immediate indicator that you need to mess with the LEDs.  If you had stopped there and ask for help, we would have asked what the DC voltage was at the tube pin with the dead LED.  If you see about 12V DC there, the LED is indeed open and the problem at that point.  If you see 0V there, then the wiring at A4/A5 is immediately suspect, as would be other loose connections around the 22.1K resistor that feeds that half of the tube.