2 ME Advanced Panel AUTO button issue

Hi, I have the panel in use live 15 hrs./day since October 2021. Since last week we experience hiccups with the auto transition button. Transition is of Mix type, duration 1 sec. Approx 4 out of 5 times the cross dissolve has a hiccup, freezes for a moment then proceeds to its end. I let it test with software control and it works fine. I also let assign ME1 to the upper section of the panel and using it there it has no issues. So I came to think that there is a physical problem with that one button itself.
Any idea? could it have simply collected some dirt inside? How to proceed for further troubleshooting or in case of dirt with cleaning?
Thanks