I don't fiddle around with the balance or fader much so its not a big issue but here goes,

AMp is fine wires are fine.

Center fader and center on balance control all it right in the world

Fader all forward is fine
with fader front right and left is fine with fader fully to the read speakers right and left if wrong very wrong both speakers work with balance centered and fader to rear but only one speaker works if you try to move from right to left ???

(This is my first Empeg with hi-jack installed if that matters)

This sounds like a wiring problem at or after the amplifier, such as miswired or shorted speaker wires. Or possibly this problem.