Completion: eventually. We had to come out on the hard, disconnect the prop shaft and slide the whole stuffing box off. Easy to remove studs then. The delay was in getting two 5/16 bronze studs made up. An hour to put the whole lot back together.
Due to launch this afternoon.
Thanks for the help everyone. And thanks to Dale Boatyard for mostly being quick and efficient. TBF the delay was not really their fault.