Right ear works randomly

I have a problem with this headphones. The right ear works whenever it feels like it.

At first it started working again whenever I “tap” it from the side. Kind of hard. But now the “punch in the ear” technique does not work SOMETIMES.

It is so random that is hard to diagnose, sometimes they work flawlessly for hours, sometimes the right ear stops working 10 times in 30 minutes…

I opened them to see if any cable was cut but they all look fine to me.

I have them open in my desk right now if someone needs a photo of them.

Thanks.