(Don't let it irritate you that he sells the chips as Cheetah MS6 replacements, the Cheetah was more or less a Matrix-1000 ripoff, and the chips are the same.
Hint: before ordering, rotate the chips to find out whether it's really the CEM3396 that's faulty. Activate Voice Display Mode (Ext. Func. 7, Number 1) to find out which one is the culprit.