NL4 one key triggers "late"

[Execbat]

Hi,

is there something I can do myself? I am not familiar with the key mechanics of the fatar keyboard.

One key (lowest D#) triggers slightly later than all the others. All other keys trigger just before the key reaches the bottom position. This one has to be gently pressed a little more after reaching the bottom. It's not apparent if the keys are played with medium or high velocity, but if you play softer, it is noticable that this key trigger after the others, or not at all, f.e. in a chord.
Are there any sensors etc I can adjust myself?

[Artico78]

I think some dust gone under the rubber contacts, you have to clean them

[Execbat]

Are there ressources on how to do that (opening the synth etc)? Thanks!