When I opened it up to check the physical sizes of the caps I noticed that the 2 big cement dropping resistors for the HT supply looked like they may have gotten a bit warm and might be worth swapping out.
![Image](https://i.imgur.com/31e49SF.jpg)
(180R 7W and are R112 and R113 on the 8080 schematic if your curious)
Looking at them they have clearly gotten warm, but it's a 7W resistor so it's dropping a lot into heat by design.
The Zeners that do the +/- 15v regulation for the rest of the amp look like they have gotten a tad warm as well so will order some new ones and lift them off the board as well.
I've never done amp work before, but am generally good with electronics work so just wanted to check I'm not replacing stuff for the sake of it given the reputation Marshalls PCBs have for lifting pads. I've watched enough Lyle Caldwell videos to hopefully do it correctly but the best way not to damage things it not touch it.