Need someone to look at my Dynaco 70

Happy New year,

My modified Dynaco 70 has started popping the main fuse. It also blew the rectifier tube (GZ34). I installed another fuse and tube and after playing for a while, it blew the same fuse. I didn't install another rectifier tube, deciding it'd be better for someone to see why the tube is blowing before potentially wasting a new tube. I am in the Sacramento area, does anyone know a person who has the expertise to diagnose what is happening?

Thanks in advance.