I am speaking from experience. My 846 died three weeks ago and there is no reason to call Shure first. I did call first and all the man said was full out the form, include a copy of my receipt and the IEM and that was it. He suggested sending it with tracking (as the form stated) which I did along with $1000 insurance. I sent my on Monday and had a replace that Friday by 10:30am.
And who paid the cost of shipping? Also why do they not answer their phones/emails at the very least to acknowledge this is what needs to be done??? Why do I need to go to a forum online to find that out?!