Low B+ Voltage

[vts1134]

I'm in the middle of a 630ts restoration and I've run into a problem that I need some help with. The schematic below shows the end of the power supply circuit. The screen grid voltage supply is +135vdc. My +135vdc supply is very low, in the neighborhood of +60vdc. Is it more likely that something is dragging down the supply downstream, or that I am not receiving enough voltage upstream? What steps can I take to narrow down the problem?



Thanks for any help/advice you can give.