I'm using the latest firmware 1.2.4 and as advised by some I have just performed a full factory reset. After this the problem is still occurring.

This seems to be a hardware issue with the rotary encoder. Try moving the Super Knob and observe the values, if there is no jumping, you can pretty much conclude it is an issue with that particular rotary encoder. Either way you should have it looked at by an authorized service center.

Yes, it is indeed a hardware related issue. Because of that I had my unit shipped to an authorized Yamaha service centerin the Netherlands and today, after 4 weeks, I got the unit back with the following report.. .. snare roll.... "performed factory reset ".

And yes, as expected the problem is still there, nothing has been fixed at all!

Heavily disappointed about the quality of this repair center as they didn't spend the required amount of time to really dig into the issue and just thought that I would be a stupid user who doesn't know how to factory reset or firmware upgrade his machine. A month without my instrument has a huge impact and now I have to go into the same process again all from the start.

They should have replaced the faulty rotary knobs as this is clearly a hardware related issue, especially since the problem was there right from the start when I took it out of the box.

Sorry to hear about your experience. Here locally, there's a music store where you can see the repair tech soldering away and diagnosing on the main floor. It's local, so I would drive there and drop off the keyboard when I can show the problem to the tech.

Not sure which of these four you used (Music Service Center in the south, Eeka Organ Repair in the SW, Organ Electronics - sort of central, or Hartlief Organ Service in the NE). When I did a search engine lookup, the Music Service Center came up first.

Just an update to close this topic. To my surprise I got a call from Yamaha HQ Germany offering a full replacement of the internal electronics board to fix this long outstanding issue. They instructed Organ Electronics in Lelystad (the Netherlands) to personally come to my house and do the repair at my home. Last week this all took place and I finally can say that the issue has been resolved. It's interesting to see how this all ended up with Yamaha HQ calling me, but most importantly I can now fully enjoy my Montage again. Case closed.

Excellent... please enjoy your Montage! Sorry for the inconvenience.

Thanks for updating the forum. It's nice to hear about when things go right.