T480 has problems with left audio channel

[vb.]

T480 with Windows 11.
I have a weird problem with my minijack port. After plugging in my headphones or external speakers, the left channel doesn't seem to work. Only right headphone/speaker would work. But when I play music on 100% volume and I start to change it from 0% to 100% really quick, after 5 seconds the left channel turns on and everything works perfectly. Then after ~10 minutes it turns off again and I have to do this weird trick with changing volume. Any ideas on how to solve this issue? I tried with Windows audio tools (channel balance) and others, but nothing seems to work. Built-in speakers are working without problems.

[RealBlackStuff]

Check if there is any corrosion inside that port.

[vb.]

I checked and the port seems to look fine as well as the other ports.