Monome problems (column brightness and button response)

Hello,
I bought a second hand monome varibright (wooden enclosure) and I have noticed that some button do not respond quickly and that some columns are less brught than other (faint light in one of them)

Did you experience this with your beloved controllers?
I know that I can cleas the button pad but I would also resolve the light issue without need to replace the leds (hopefully).

Hopefully you can share your knowledge/experience

THank you
Sero

post a photo regarding the brightness issue.

re: keypads see http://monome.org/docs/care/

Thank you very much for replying quickly, much aprpeciated.
Sorry for the late reply but I have been caught by work.

Strangely this does happen only when I use one specific user on my laptop (the one supposed to be used only for music) but if I run max on my “work” user there is no issue with button brightness.

Also I have noted that monome sum creates this problem (when I run it and then run max I have this issue…also if I use the maxforlive monome suite).

I have tried removing monome sum and the issue goeas away but as soon as I load ableton (my template contains monome m4l objects) the issue comes back.