I'll check the drive belt's tension. I did loosen it slightly over the factory setting....but the sound is new after quite a number of miles since the retensioning.
I do have a GoPro and have used it to post a drive in the M3W and used it diagnostically on my airplane to confirm what the main gear doors were doing when they were supposed to be closed. It's a possibility, but I'm not expecting enough movement to see anything.
As I said, I can grab the roll bars and rock the M3W--no sound. Just when I take my foot off the accelerator and the weight shifts forward. Drive belt seems like a possibility.
