Noisy StingRay

I’ve sent this to the customer service chaps, but I want to lob it here, too, just in case someone’s up late and knows what the problem is 🙂

Today my Neck-through StingRay suddenly started making a noise like the thoka-thoka of helicopters.
The sound has settled down into a random scratchy crackle, sound file here.
Further observations:
1. I’ve tested it with a different lead and a different amp, it’s definitely the Bass.
2. The noise is constant and is not affected by any lead jiggling. In other words, left alone, the bass makes this noise constantly. The sound file is with the bass just sitting on the table, no jiggling.
3. The noise is affected by the Bass’s EQ and volume.
4. Under the noise, the Bass sounds fine.
5. I’ve opened up the back plate and there’s nothing that looks obviously unattached.

That’s as far as I’ve got.

Does any of that ring a bell? Any idea what it could be?
I’m not comfortable rootling around in the electronic bowels of anything, so layman’s terms, if you please 🙂

Time is tight if I need parts from the USA. Next gig is 5th may.