Yamaha DX100 headphone audio output not working

Hello, On my Yamaha DX100, I have a problem with the headphone output (the line output works). Do you have any idea where this problem could come from? I’m thinking of a power amplifier problem, but what electronic part should be replaced in my DX100? Do you have an idea ? Thank you for your help.

I was able to repair my Yamaha DX100 synthesizer. I found the electronic diagram on the internet. There were several broken electrical tracks on the circuit board. At first, I thought it was op-amp IC23 that was dead (circled in blue on the schematic). I replaced it with an LM386, but that didn’t change anything. So I looked at the diagram carefully and I said to myself that there must be something wrong between the audio line output and the input of this operational amplifier (red electrical conductor on the diagram). I used an external amplifier with a tip to probe the audio at different places in the electronic circuit. There was indeed audio at the output of line amplifier IC21, but nothing at the input of amplifier IC23. So, I looked with a magnifying glass and I could see several cuts on the electronic circuit that I repaired.
(I could not publish the images of the repair, sorry the website forbids me)

Everything is ok now.