I'd remove the head keeping the plate on. When screwing on the fittings to the new dampers, you might wish to orient them so that they, when torqued a 1/4 turn to not end up under stress causing them to want to untwist. In other words, look at the destination of the line "as a relaxed line". Then loosen and retigthen your fitting so that it naturally falls to that position. I've got a tech that also recommends simply pulling in ink from the bottom tube coming off the capping station, instead of running fills.