I would call Sonos Support directly to discuss it.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

Somewhere there is an intermittent connection. The “small shock” (an arc) will transfer a small ball of metal and bridge the gap, but it’s a very fragile connection. This gap could be obvious after a visual inspection or buried inside a component. I’m not familiar enough with PLAYBASE,  but this could be a familiar failure mode for components of a certain age. While locating the first failure of this type can be frustrating, eventually it could become a “usual thing”. Any unit displaying this symptom then gets the “standard” repair without spending much diagnostic time. Large service shops often know what’s wrong as soon as they recognize a model number. This does not necessarily mean that all samples of this model will fail, but those that do fail follow a known pattern.

Thx for the reply.

Now I dont know what to i should do with that. 

If you are into DIY repair, there may be some info online. SONOS does a not provide repair services. There are some 3rd party repair companies in the UK and EU.

Before DIY call Sonos they may have an offer to help if the speaker hasn't been opened.

If you open it, since a bump works, suspect a connection. You can slightly slide each connection out and back in to see if that cleans it up. Not much more than a small wiggle.

I think i will not open it myself, too much of a risk.

Thanks for the advices !

Let me know if you get a solution.  I will see if it works on my teenage son!