If you're having trouble establishing a mind-muscle connection with your triceps then begin the workout with something that puts the muscle into a shortened position, and work isometrics (holding the contraction) to help with that. Try a pushdown variation. My favorite for this is the reverse-grip pushdown.
Make a concerted effort to roll your knuckles back towards your body and hold that for a 2-3 count for 3-4 sets.
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