The igniter is located under the tank toward the rear on the right side of the frame. Some may be mounted on the left, but I haven't seen any. It's a plastic box about 2 inches or so square, maybe 2 1/2 - 3 inches tall and part of one side is sloped inward.
Pop the tank off and locate the igniter, then button up the bike and run it untill it starts acting up consistently. Spray some electronic cold spray (available in electronic supply shops including some Radioshacks) up under the tank where the igniter is located and see if it temporarily fixes the problem. If it goes away until the module warms up again, you can bet it's going bad unless there is a contact problem in the big plug on the bottom side.
