Sorry you're having touchscreen problems. I've had the same troubles with my MODX7 on and off for a while. Because the problem is intermittent it's much more difficult to solve (froze on the gig but worked fine at the service center). I'm sure you've tried this but sometimes turning the keyboard off and on again (reboot) works and sometimes it doesn't. "Just calibrate the touchscreen": if the display is non-responsive you can't calibrate the touchscreen because it doesn't respond to touches anywhere! You can use physical button combinations to access most of the items on the screen to keep playing at a gig if you need to (but not those on the far left of the menu on the MODX: you are able to access those on the Montage). Because my MODX is long out of warranty I opened the case and checked the display cable connections thinking a loose cable might be the problem. All seemed tight but I may check them again. I also tried going back to older firmware versions but that didn't seem to make a difference. I suspect it's somewhere in the hardware and until I figure it out I'm relying on button combinations to change voices and do what I need to do. Sorry I can't be of more help.

This is the biggest single fail in the design of these instruments.

They're not fully navigable without the touchsreen's touches.

With direction arrows and enter, exit, increment and decrement, and a cancel-ish button, and shift button (all of which both the Montage and MODX have) the entire UI and operating system should be entirely operable without ever needing to touch the screen.

This is most important from an accessibility point of view (vision impaired etc), but also from the perspectives of rapidity of navigation, sureness of navigation in live settings, and for if/when the screen's touch responses fail or are otherwise suffering.

And because the screen's brightness can't be adjusted, in those light settings when it's painful to look at the screen (dark environment), or difficult to read it (sunlight), this would solve those problems, too.

It's odd that they haven't fixed this.

I guess you're only having touchscreen problems if that's true. A freeze can happen where the issue isn't the touchscreen. Because physical buttons would still work and take you HOME or otherwise navigate around when a "freeze" happens that's just because the touchscreen isn't working.

I don't disagree that the UI should work with or without touch -- because I personally dislike touch, I avoided getting a MODX due to lack of physical buttons on the RH side.

At any rate - if when this freeze happens your physical buttons are not responsive and knobs no longer show status then it's unlikely that recalibrating the screen is anything you need to do. I don't know one way or the other.