This is an Oahu Amp, 1941 (probably). There aren’t any date codes on the amp, as that didn’t really start until WW II. The circuit has a 6N7G dual triode for the first stage: one triode for each input, 6C5G triode for the second stage, then a 6N6G internally coupled triode and power triode. The 6N6G has a resistor in it to provide the grid bias for the power stage. A 5Y3G tube acts as rectifier. This amp looks as if it were brand new. Compare its condition to the exact same model picture in the book “” by Aspen Pittman, page 46. That’s extraordinary for an amp that old. I replaced the electrolytic capacitors, and it came back to life, and sounds great. The last two pictures show it after and before cap replacement. Note how large the old capacitors were!