Customer states that TLAudio FatTrack mixer is cutting out after a while, and wanted a valve swap for something better.
Found MPSA42 getting extremely hot exceeding 100deg C and breaking down (this is part of the HV circuitry for valves), even with small heatsink attached it was still 86+ and clicking out of service:
The spec for this component should be max operating temp of 150C so was replaced with new. As this is directly underneath electrolytic caps in the operational orientation, those were replaced at the same time whilst the board was out.
Now the unit runs without dropping out. Unknown 12AX7 valves replaced with JJ long plate which seems to offer a slightly warmer and smoother sound when driven (quite a bit subjective though!).
Still not 100% happy with the temps etc as voltages a little higher (unit designed for 230V and we have 250V+ quite regularly here in the UK), but there was no quick fix for that.
Metering etc was calibrated as was off a little, and returned to the customer, suggested to run on the power conditioner which he was testing so help keep waste heat down.
