Yamaha AX-900U

Holding steady at 5mv. The other channel is 4.8mv. This after 30mins.
I still in awe this darn thing is working, I had given up hope that I had the skill set to fix this. I am just wondering why all of a sudden it decides to function properly
After I had reinstalled all the transistors thought it would be prudent to clean the solder side of the main board. I brushed it down with a brush and 90% alcohol and then took the air conpressor to it. Wondering if there was a small piece of solder caught somewhere