LOST LF CHANNEL VIA RCA

Anyone loose a RCA connection but balanced connection still works?

Probably either a defective cable or a broken solder connection on the RCA jack in question. The balanced output is fed from the unbalanced line output, ahead of the physical RCA jack.

There's always the possibility that the receiving equipment might have the defective jack too. If you've swapped the cables and that output is still dead, you'll need a repair.

thanks
its not the cable so it must be the connection