To Ga Rebel, I bought my first Apex immediately upon their release, and shortly after I acquired a second Apex. And then, having three search coils other than the standard Viper coil, I bought my third Apex. Of the three, one of the first two was a bit noisy and I sent it to the factory for service, and it was corrected and returned to me working fine.
In early to mid March I acquired a fourth Apex and that one keeps the factory standard Viper coil mounted and I have it on-hand for friends and family as a loaner unit. It also functions fine.
As for raising the detector and coil in the air and shaking it around, yes it is not uncommon for that to create noise. It could be due to the shaking that involves loose wires, but it is mainly because the coil is held in the air where it is more susceptible to outside sources of EMI influence.
I've been using my number one Apex with Ripper coil and my number three Apex with a 5" NEL Double-D coil here in my yard the past month and a half. This is a half acre lot in the city and there are times when I will operate at full sensitivity with little or no chatter but most of the time it gets just a little noisy and I need to reduce the sensitivity two notches from Maximum. If you have the opportunity to try a different coil on your device that would let you know if it is a coil related or a coil connector related issue. Also, if you have reduced sensitivity a couple of notches and that does not resolve the problem then I agree that the Apex should be sent to the factory for service.
it's really a very good detector and you just need to get your noise issue resolved.
Monte