Reach them through three routes: trade association member lists you have never quoted, attendees at shows where you already exhibit, and referrals from existing customers into their peer network. Keep the question set short, since they have no experience of you to describe. Ask who they call first for this kind of product and why, what would put a new supplier on their list, and whether they have heard of you and what they associate you with. That last question distinguishes a positioning problem from an awareness problem from a reputation problem, and each one calls for a different response.