One key is playing differently than the rest

[pkpkpk]

Hi, On my Electro 5d, all of a sudden, a random key (Ab above middle C) is playing at a completely different volume than all the rest. As if the velocity is set to maximum. I have attached a 4-sec video clip. Is this a common problem that I can address, or will it need to be taken in for service? Thank you for any help with this!

[harmonizer]

I did not watch the clip. But the symptoms you describe resemble what happens if you get a tiny piece of debris in one of the contacts for that one key. I have taken apart my Nord Electro 3 twice to resolve such a problem. The spec can be incredibly tiny. In my case the spec was so tiny that I would not have noticed it, even after I had the keyboard opened up with the contacts visible, unless I already knew there was something wrong at that specific key. There are videos on youtube that describe how to open up a Nord Electro, and then open up the keyboard mechanism within, peel up the rubber contact strip, and thus gain access to the area where the spec of debris may be present.

If that specific key plays normally for organ sounds (which are not velocity sensitive), but you have the problem with piano patch sounds (piano, EP, clav), that would increase the odds that the cause of this problem is a tiny spec of debris on the contact for that key.

Some people are comfortable with doing the kind of work shown in the videos. You should judge for yourself whether you are one of those people.

Video instructions for Electro keyboards that have waterfall keyboard actions (as opposed to ones that have weighted keyboard actions) tend to be similar.
I recall using video instructions for taking apart an Electro 2 73-key model, with my Electro 3 73-key model.
Weighted keyboard actions are more complicated, and different.
Also, if you see any videos about this for the Nord Stage, that is also a more complex beast - it might have more cables inside it.

[harmonizer]

Just watched your video, and I am still guessing this is dirt in the contacts for that one key.
I'll bet that playing a clav patch makes that key sound terrible as well.

[pkpkpk]

Thank you so much for the advice, I will follow up! That was very helpful!