Excessive hiss/white noise in one speaker

[Shentity]

I recently purchased a pair of second hand Mackie Thump12 powered speakers. I expect there to be some white noise coming from the tweeters on the speakers, but one of them is significantly louder than the other (can only hear one within about 2-3m when no music is playing, but can still hear the other one from across the other end of the garage around 10m away). This is regardless of whether or not the speakers are connected, and the level of noise is not affected by the gain unless it is near max level (around 80% plus). I've swapped the speaker locations/connections and the noise follows the speaker, so there is clearly an issue with that particular speaker causing this.
Any thoughts/guidance on what the cause(s) might be?
Have read that failing capacitors could be the cause of noise, but unclear if this would relate to white noise specifically or only some other frequencies as the discussions I have been able to find refer to 'buzz' and 'hum' aside from just a general statement of noise.

 

[dasdoing]

what does the seller say about that?

 

[Shentity]

Yet to receive a response.
Having a look/listen again I have noticed the sound isn't entirely consistent, with some crackling etc. at times.
Recorded the two speakers from around 20cm in front of the tweeters to show how they differ from one-another and the kind of sound I'm getting https://www.dropbox.com/s/ue71v9x6c0k9paf/Speakers.mp3?dl=0. The first 7 seconds is the speaker that is OK, and the other speaker is from around 11 seconds onwards.
Other than the additional noise the speaker sounds fine when playing music.

 

[restorer-john]

The Class D amplifier in the noisy unit is failing. This type of random crackling is common in my experience before they go full failure.

 

[dasdoing]

yea, that is not white noise. would return them. the seller probably said they were ok? open a dispute on the platform if he negates the returning.