Issue with the Vertical Size Vsize that is jerking on its own

[hannaconner]

Hi,

I just spent an hour playing on recallbox, and now the screen starts changing/jerking the V.Size randomly. I then tested it on an original PCB (Mercs) and the same problem.

I've been able to play for hours since I've had my cabinet (1-2 years), but it's never happen before.
Does anyone know this issue, and how can I fix it ?