Faulty analog sticks - only up and down axes on left and right

Hello

Im trying to repair controler (magma red version) with faulty analog sticks.

Only vertical axes are dysfunctional -they go both “up“.

I connected them to PC and its shows me this in neutral position:

Also if i put some pressure to right stick - like almost hitting R3 it then stabilizes like it should work in neutral position - and funny thing - pushing it also affects the

What i tried to do is clean potentiometer “disks” on both those axes. It didn’t changed anything.

However sticks look like they are covered in some… slime or oil.

I recorded it and sent it to youtube.

https://www.youtube.com/watch?v=Wokj0D1p...

If you look closely you can see its almost glowing.

So my question is - is it some kind of oil or lubricant put on purpose or can it be soda someone spilled out?

I opened about 3 or 4 dualshocks and have never seen something like that - however i havent yet seen sticks with black plastic parts - only those “white and green type”

I also found something like this near charging port and i was able to scracth it from PCB (no harm done).

So if it is some soda how can i clean it?