Numbered patch/arp keys "sticky" on original Micro

[AEJOTZ]

when I got my used original Microkorg in 2011, every control worked perfectly except the 3 button, which was a bit stubborn to actuate sometimes. I put up with it because it was really no big deal.

But now, in 2017, the 3 button works fine and two other numbered buttons are acting like the 3 used to. I noticed this after turning the board this way and that while cleaning it, as if there was something sliding around loose inside and getting partially between the button contacts and the circuit board beneath.

Before I start disassembling the unit I'd like to know if anyone else has dealt with this problem. And any warnings before I take everything out to get to keyboard?

[OpAmp]

Hi,

Get some inspiration here:
https://www.youtube.com/watch?v=uSvgQgFKIxs
https://www.youtube.com/watch?v=fsd9y9z781U
http://furrtek.free.fr/index.php?p=crea&a=mkorg

Good luck