Super Famicom flickering display

Hey all,

I have a switchless modded SFC, which over time has been getting worse with flickering.

It used to flicker a bit then settle down after 3–5 mins, but now it doesn't settle and stop. It appears worst when there's large areas of white/bright colours, eg, the intro to SSF2 is mostly ok, as it's mostly a black background.

Here's a Vine of how it looks — https://vine.co/v/MlnbVl3ibBe

I've tried via SCART and composite, on different TVs, with different cables (and different power supplies).
I think the video chip is on it's way out. Any more considered opinions?

cheers