It will work there, just screw it on with some new thermal compound. I would also check the 4 mains diodes D13 to D16, one looks kind of odd looking, and bears checking out if it is shorted or open. I see you took C15 out, was that because it was bulged or just to get the transistors out. If it was bulging then change the other one there as well, 120uF 200V, as they really need to be close in value and ESR for best results.