Weird TEX 88 issue with volume

[Mezzopiano]

Hi guys, i recently got my hands in like my 4th TEX ever, this one i got because i wanted to fix it and sell it

The problem is, there is no sound via Outputs, but if i plug in my headphones via headphone jack, there is sound coming but barely audible, you have to really pay attention to hear it

The potentiometer works, the day i bought it the previously owner told me that suddenly it stopped playing, but i can hear the click on the touch and everythings seems to work fine, minus the sound

Anybody has had a similar problem?