CRT monitor power issue

[Dagare]

I saved 4 monitors from the bins a while back, this one (proview ije558) worked for a couple of months before failing, started with what I can only describe as a boot loop, before dying completely.
I've spent some time working on it and have managed to get power back on after replacing a faulty cap and MOSFET.
When no image is displayed, it powers on as expected, static in the tube, degauss etc, but when an image is displayed, it goes back to the "boot loop" where it clicks on and off rapidly.
I'm assuming this is still a power delivery issue, but I'm not sure where to check from here.
If anyone has advise I would be grateful.