Philips were actually enormously helpful. I just called them up (well, after going to a TV repair shop, picking the guy’s brains, and getting the number from him), got through to their technical service dept, got them to send me the full service engineer manual, schematics and all, and they were happy for me to quiz them on likely root causes - like, the guy I spoke to a few times seemed genuinely excited that someone was actually trying to repair a TV, and correctly pointed me in the direction of a group of oscillators, one of which had a blown cap. Fixed the thing.
Lived on the wall of our office for a decade until it fell off one day. On me. There’s karma.