I'm convinced that at least half the shutoffs/nosedives are from worn out or wrong shoes. I had a nosedive, sent the board in, got it back and it still felt a little "funky". Then (and only then) I remembered that the board was acting up a year or so ago and I just happened to get a new pair of sneakers at that time. The board stopped acting up. So this time I bought another new pair and the board stopped it's "funkyness". I sure wish I'd thought of that before I sent it in. Before the nosedive sometimes I'd have to try several times to get the motor started. Try new shoes and maybe save yourself five hundred bucks.