My guess is the vertical deflection amplifier is toast. The repair requires replacement of the vertical output transistor and perhaps a few other components surrounding this circuit. Sets this
Failure of the convergence circuit is very common for all RPTV regardless of brand name. Probably, you will need to replace the STK chip - which is often the cause. There are convergence repair kits
Is sound ok? If so, it may need replacement of the main board. They cost over $50 and require a little electronics experience to install. You can usually find them on shopjimmy.com or such places.
My first reaction is to have you take a look at the settings for the various playback modes and make sure they are all congruent with what you are expecting. This set has many settings for various combinations
It could be a technical problem requiring a repair or adjustment - which would require taking it in to a JVC authorized service center. Or, it could be a compatibility issue. The specifications on this