It turned out to be a short circuit in a decoupling capacitor in the 20MHz circuit causing the -15V supply to drop and the burned was an inductor that was slightly burned but still OK.
Replaced the cap but as the backup battery has been poor lately I left the box open and will get a new battery tomorrow and replace.
Repaired the burned 70cm preamp and it works but the noise is slightly higher but it seems stable so I am good with that.
Tested a 2m YU1AW and a 23cm G4DDK as well and it correlates to earlier measurements so nothing else seems wrong with the meter.
|2m YU1AW Preamp|
|G4DDK 23cm preamp that I have spent some time with.|