Not powering up

Hi, just bought a Gpdi/IR of Reverb. Sold as excellent condition. Unfortunately it does not fully power up. Power light blinks, indicating tubes are warming up, only to then cut out (I hear a click, clip light briefly lights up and the IR lights turn of and on again), and then turn on again. All of this on repeat…
Any suggestions, besides returning the unit to seller?

Hi Gert,

This seems like an issue somewhere in the power supply. Probably the main 12V supply.