I own a Matrix-1000. Only recently, I noted that one voice only seems to have only one oscillator running. Ran test program, identified the faulty voice, moved the Curtis chip, problem moved with it. Conclusion: chip seems to have died. (And I thought properly treated chips never did that.) So - no other way than to replace that thing, right Anybody here who had the same problem  

On a more positive note, I succeeded in desoldering the 68B09, putting in a socket, and putting it back in, so I can seriously consider trying Gligli's fast processor mod with a twist .