Visual problems with CPC 464

[DarkDalamar]

I brought this one back to life, and everything is fine, the Datasette loads, software works without problems but, but this 464 has an problem.
At first, never seen this (i have another 464 and 664) on my monitors (one colourmonitor and three monochrom) before, and after minutes, sometimes even seconds, the colours are changing and letters are like this:

[Bryce]

Things that happen after a few seconds / minutes are almost always a temperature problem. Sooo...

A) Does the Gate Array have a heatsink attached?
B) Can you try the Gate Array from your other 464 in the machine and see if the problem goes away?

Bryce.

[DarkDalamar]

Bryce, no, not even try to replace it, but thx for the idea.
And yes, there is this heatsink plate attached.
At first, i will try to change them. ;-)