I have tried all the basic troubleshooting - swapping power tubes between both sides, swapped the EF86 preamp tubes, replaced the middle 12au7 preamp tube, swapped speakers, as well as trying both the 4ohm and 8ohm outputs on the bad side, none of those tests made any difference. I have also gone over the circuit multiple times to make sure it matches their build instructions.
Before attempting to bias the amp, I tested the voltage at pins 3 and 4 of all 4 output tubes and it measured 495V, I noted that the bias points were at 0.31V. I also noticed that if I have speakers hooked up while I am testing voltages, the one on the right side makes a slight pop sound while the left side makes no sound at all from this.
I then tried to bias the amp to see if that would drop the voltage a bit at the output transformers because 495V seemed high, according to Triode it should be between 375V and 475V (I am not sure if this was even a logical troubleshooting step, but I was not sure what else to test). Once I get both sides over 0.9V the fuse will blow every time, but may last a minute or so. Also, when I do both bias pots near or over 0.9V, the bias pots are nearly at their max, so I am not even sure I could make it to 1V if the fuse didn't blow.
I saw that there was some troubleshooting info on this site (which I literally just found this morning!) which I will go over when I get home from work tonight. I will definitely give the output transformer test that Bob posted a try.
Based on the info I provided, am I right in thinking that the output tranny could be bad? Could there be something else wrong? The only other thing I could think of is that maybe there is a short on the bad side that I cannot find?
Thanks for any help!