Expression Submaster level

The only option that I saw was to use the Grand Master as a Submaster Master.  If that setting was used and the pot on the GM is a little dirty, maybe that would be it.

Also, it could be a dirty pot on the Submasters.   Does it do it on any of the 13-24 subs?

Have you tried a deep clear by switching off the console and holding down 789 as you turn it back on? 

Good Luck!

I'll switch to my backup console.  789 clear the shop can do.   I think its the output on the submaster PCB.  I can see the output level varying between 95 and 98% on all faders that are engaged.

If all of the sub pots are behaving exactly the same, then it could be that the calibration pot is off.  It's unusual for it to change on its own unless it was damaged, but it's certainly worth checking.  It's located on the underside of the facepanel circuit board (the side you see when you open the console) and should be labled P6.  You'll need a small screwdriver to adjust it and it's a 10 or 20 turn pot so you may need to move it pretty far to see a change in level.

As I looked back to refresh my memory of how the part was labled, I noticed that it also affects the grandmaster and the playback crossfaders.  If those are working correctly, then your problem may be elsewhere.