I think you're making it too complicated. If you mess with the actuator, make water come out when some are watching, they will come over to investigate because of their curious nature...unless they are scared to death of you.My chickens did not figure out their new watering system, but we are only on day 2. The first day, one hen pecked at the red part of the vertical nipple but didn't get any water. I'm not taking away their regular water dish just yet, but had a small success today:
I cut up very small cubes of banana and pressed them onto the nipple. It took a while to get them to stick, but once they did, the hens came over to eat. The banana disappeared without much release of water, but it got the rooster's attention and he came over and started drinking. I saw one other hen take a drink, so I am hopeful that if I remove the water dish and try more banana, they'll be onto it. Just thought I would post this idea for other people with nipple-resistant chickens.
The banana just mucks up the watering device with sugars and bacteria. This is just my opinion though, so you can take it or leave it if that is what you prefer.