WG 4600 Rpi2JAMMA screen wobble

[Strawdog]

I recently got the awesome RPI2JAMMA by AJE, I have one problem, though, i am seeing the screen 'wobble' slightly, its very noticeable when it boots and is in the menus.
I have a Black Tiger pcb and a Rastan pcb, no wobble on these. any tips would be great!
thanks

 

[Firehawk]

I have the rgb-pi in an Astro City and for the menus it also wobble/vibrates a little bit. When I boot a game it's gone.

 

[Strawdog]

For me, some games when they boot it disappears however not all, I’m wondering if this is a monitor power issue? I’ve got a 100v output monitor isolation transformer in my cab . Just ordered a 120v output one to see if this resolves the issue.