I will take voltage readings asap and post. I was too busy playing last night
I agree, it could be a tube. Just running the originals right now. I will try to reflow my joints, but its just so packed in there I hate the thought of tearing it apart.
Rectifier isn't going to affect the tone but in certain situations can sag so if you want the amp stiff use SS plug or 5u4 or GZ34 which increases the voltage to the power tubes and preamp without sagging out under load.
Higher quality rectifier tube makes a difference. The amp uses the 5Y3 which I would think would be the ideal choice.