I have Hampton Bay track lighting in a bathroom and now two of the heads will not work, I have replaced with new heads and still will not work, can move the last two heads that do work to any place on the track and they work. Have replaced bulbs with one that have confirmed working.

Pull the ones off that aren't working. Take a look at their contacts, and the contacts in the track. You may want to shut the power of for that. Do the contacts look like they should touch the contacts in the track. Is everything the same model? Use an ohm meter or test light to see if the contacts in the lights show continuity. If they don't even with known good bulbs, take them back.