PPI AX606.2 right channels low under load

Strange issue. Under no load, all channel pairs Front and Rear pass the same amplitude signal at speaker terminals. If I apply a 4-ohm load, the right channels output about half the amplitude of the left channels.

The sub channels seem to be OK.

I checked feedback resistors and top controls. Any thoughts?
No the audio is not distorted on scope nor speaker.

Yes the right channels are lower than the left for CH1-4.

Yes lower voltage on the scope, and lower volume via my ears.

The left channels stay at the same amplitude when no matter if loaded or not. The right channels unloaded have the same amplitude as the left, but then loaded the amplitude gets cut down.
Yes it is.

Heres some more strange. Maybe this amp actually is ok? I'm not totally sure. If I connect loads simultaneously to the L and R channel sets, then both channels output 100% equally. It was only when I loaded one channel at a time instead of both when the output was reduced on the right channel. Strange?

I'm going to put this amp back together and test in channel pairs instead of individual channels... I never had to do test like that before though.

Almost as if the feedback circuits are crossed????