Hello everyone!
    I'm trying to troubleshoot a Zkit1 and I'm stumped. One channel is ok and the other is weak and fuzzy.  Voltages are low at A and B by about 20 volts, C is just a bit high but not too much, and both Ds are where they should be. I've reflowed most of the solder and checked a few of the caps out of circuit,  I compared voltages between the 2 channels but no obvious differences. One thing I'm confused by is the good sound comes from the right output with  left input. Right input produces weak sound at the right output. I've got a working ZKit1 I'm going to measure/check against this one but I hope maybe someone here might have some insight that will save me the trouble. Thanks everyone!
Cheers!

I didn't build mine from the kit itself but if I had to guess it sounds like a mis-wire in the amplitude control area.
The fact you have right channel output from the left input makes me think this.
Are you using a stepped attenuator or audio taper potentiometer?