Just Leave it in the incubator until it hatches, then put in with your chicks...Even if you are using en egg turner, ITs ok to just lay the duck egg down with chick eggs and leave it alone. This will give it time to right its self anyway..
Shipped eggs are harder to hatch out anyway, All that bouncing around and some people are not careful during the shipping/handling process either.
AS far as you "incubator" getting down to 95* That may OR may not be the cause of losing your last 3 ducklings.. AS there are a 'thousand" things that can go wrong, including simply Bad eggs to began with..And Sometimes they make it to Term, but simply do not hatch. I have hatched out Chicks, standard and banty, Domestic/true Duck and Muscovy, for the past 8yrs... One time I had had the cord of my incubator get caught cross a corner, cause the lid Not to get closed all the way..after we had candled them, about 2wks into incubation, Woke up to a temp. of around 78*, candled my eggs and Nothing. Put them Back anyway and let them warm up.. All 30 eggs were still going when we rechecked later that day.
Had a Muscovy decide to brood Where ALL the chickens wanted to lay.. about 3 1/2- 4 wks later ( in early March {in Idaho}) an egg got rolled out of the nest at some point the day/night before. Found an ICE COLD Egg the nest morning. Candled it, and Nothing, put it in the incubator to warm it up, had chicken eggs going so incubator was already up to temp. 4 hrs later, we checked on it, AND that was the Happiest Little Duckling You ever did see. WE marked the egg and gave it back to Mom. YES!!!! that "Little Guy" hatched TOO..
Then there is the 1st time stuff... I did get lucky though, out of 39 eggs, we had 11 hatch, But the biggest part is Our Incubator, like everyone, else's DOES NOT run the "scientific way". AND that is the hardest part of incubating, Learning HOW your incubator runs.. so you dont drown your Babies.. or dry them out to much.