Alle Fish

I tried with Montarbo and Warwick amps, hi and low gain with 3 different cables but results are the same:
No sound with l/mono output , sound with headphones output 

Hi everyone!

I have some problem with mono output of XWP1. 

I never had trouble but one day suddenly stopped working, I checked jacks and other outputs like headphones and goes correctly. I turned up both keyboard and amp volumes but you can hear a very weak sound  . 

What's going on?? Thanks all!