The most common tactic to start with this, is to measure the voltages for the correct levels on the main board connector J119.
Afterward it will need to replace all the electrolytic capacitors on both boards of your power supply. The same exist and for five yellow capacitors branded as Rifa there.
There is X and Y 275VAC types.
But think twice before you spent a penny for this!! Have you a way to do all the calibration by yourself? It need very specific and time consuming procedure for this, plus very expensive calibration tools.
There is also a case of needing some original TEK genuine spare parts.
I'm not trying to disappoint you. But I say things the way they are. ;-)