Hi - to follow up on Natrixgli’s comment, I do hear this same noise in my A4 but it is much much less noticeable / loud, and the A4 has air vents. It’s almost impossible to hear it on the A4, but it’s there.
I have had a couple synths over the years that had a loose screw or a broken piece of plastic stuck inside and it sounds like plinko when when rocking it back and forth. This almost sounds like that here on the Octatrack but I can’t quite tell for sure if it’s something that is falling all the way from one side to the other or confined to a small space.
I think the rattle noise I’m hearing is something intrinsic to the mechanics of the buttons and/or knobs. It sounds like little loose mechanical pieces contained inside “something”. That’s the best description I can come up with. When I rock it a little hard the rattle noise sounds like multiple little “pins” in unison moving around. When I rock it slowly the “pins” all move and make little noises at different times.
I did ask a local to me Octratrack expert, Mark Mosher, and he too stated he did not hear any rattling noise in his other than the CF card reader ejector button makes a slight noise, as does the one on mine. So, the consensus is this is abnormal. Natrixgli has kindly offered to refund my money after I ship the unit back to him for him to address the problem and have it fixed.
Numina