Megatouch monitor: H-Size doesn't work

I have a Megatouch Maxx with a monitor that I can't adjust the H-Size on. All the controls are on a remote adjustment board, and all of them work -- except for the H-Size pot.

I'm almost certain the pot is okay; it reads 0 ohms at one extreme and around 50k ohms at the other.

Any thoughts? I REALLY hope I don't need to replace the monitor; it works fine minus the sizing issue.