I also found this sync stripper to put nicely into as cart plug
https://videogameperfection.com/products/sync-in-scart-board/]Sync Stripper
Today I received the capacitors, I immediately replaced both leaking ones on the power regulator boards (5V and 12V).
At least the regulators are staying much cooler now but unfortunately it did not resolve the blanking/shipting problem.
The sync stripper takes some more time to arrive but once arrived and installed I will come back here with the results.
Yesterday I also received the switches for the cursor buttons.
I immediately stripped down the computer and removed the keyboard from its frame.
I de-soldered the 4 existing buttons and replaced them for the new ones and tested them.
They work beautifully and was worth the hassle.
[answered in the wrong thread]
What switches did you bought and from where?
Hi Popolon,
I bought the following switches:
Würth Elektronik WS-TSW 430456043736 Pushbutton12 V/DC 0.05 A 1x off/(on) Momentarily from Conrad Electronics.
They were only 0.93 Euro each and they fit perfectly.