Continuing on from yesterday's video [TCE #0446], I replaced the Tesla programmable peripheral interface (PPI) chip for the keyboard, MHB8225A, with a Western CMOS equivalent. It seems to have stopped the "key stuck on repeat" issue.

However I think I still have keyboard issues. Thanks again to Jakub@jjermar1 and Yura @yurasergienko6890 for their advice.

Jura pointed to a Hungarian video by@ATLAB where he details about replacing the rubber domes, and also identifies a replacement from Aliexpress:
   • PMD 852 számítógép javítása. 1.rész ...  

On Aliexpress they are described as ... "Φ12*Φ7*H6mm silicone conductive single keypads silicone buttons" ... so I'm thinking 12mm outer diameter, 7mm inner diameter and 6mm height ... ? This one page (that exists as of May 2024) they are "model DGQSDZKP58" ...
https://www.aliexpress.com/item/10050...

https://archive.is/0Sk09#selection20...

I'm really wondering if designing a replacement keyboard might be a better solution ... ?

Time to have a look at the Robotron Kleincomputer KC 85 again I think ...