Yes - I left RF intact and just disconnected the coax cable, I'm about 90% sure it had this issue beforehand, I remember I was hoping it would go away with the UAV mod.
I've tested a few other games and oddly it doesn't have this issue on the title screen in some games but its then visible on the play screen, I'm thinking its something involved with processing and when the system is under load - bad ram, GTIA, ANTIC.
I've uploaded some other images - Joust at boot, Joust title screen and finally Joust play screen.
Thank you.