If you want to call Stern support directly, then prepare to be patient. Stern doesn't have a bank of 20 guys waiting to do support for anyone who calls in. Their sales and support model assumes the distributors are going to be the first line of support. So as others have said, make sure to buy from a reputable distributor.
What can be confusing is it can be a bit hit or miss with what the Stern support team will help you with. Sometimes when you contact them they will help you out immediately, other times they will push you back to the distributor. Don't know if it depends on who you get, or how slammed they are, or how simple the issue is or whatever.
How I approach it generally is if it is a larger issue that is going to require parts I go through my distributor. If a smaller technical glitch that I can describe in detail will try going through Stern support first.
That being said, I have contacted Stern support directly about four or five times over the years for various issues with different machines and have always found them to be very friendly and helpful.