This amp was in good working order. I had borrowed the 5AR4, for another amp, when I wanted to use the X-100 again I inadvertently, put a bad 7591 in that place( I have not forgiven myself yet). After the sparks and realizing what I had done, I put a 5AR4 in and hoped things would be okay---they aren't. For some reason 12AX7s V1,6,7and 2 do not light up, the others and the power tubes do. I believe the brown and white wires supply the AC for these filaments. How can I check to see what may be wrong. Is that symbol #47 a lamp if it was burned out could that be the problem. Thanks for any advice.