You really don't want to disturb the seal by pulling them out unless you have to. You can buy a cheap mechanic's stethoscope at some auto parts stores, or take a wooden dowel or even a long-handled screwdriver and put one end on the injectors, one at a time, of course, and the other end to your ear and listen for the ticking that will signify that the injectors are cycling. Umm, if you use the screwdriver trick, be sure to put the handle end on your ear and the tip on the injector. Could be a little uncomfortable the other way around, not to mention the potential for punching a hole in your eardrum! -TD