Have you got a variac? This is a device to vary mains input. Wake the set up gently over a couple of hours, after you have remade the LOPT casing. Cut off the capacitor across the mains as well, otherwise it may go bang and scare the cat.
When you get first light on the screen then you're almost home, as most problems are with the PSU and Line Output/EHT stages.
As far as capacitor changes go, change one at a time and test after each change. This is for two reasons:
1: One mistake with one wire and you will be driven mad.
2: You can see which make the biggest difference, which can be fascinating.
A mirror for the screen is handy as you can look at the set from behind.
I'm here if needed.... you might find this site handy:
www.oldtellys.co.uk Done by some complete idiot....
Cheers,
Steve P.