Light socket insertion into the duct is simply difficult beyond belief. Design of socket depth is such that one cannot hold the edges of the bulb, while trying to twist and turn, the flush ended bulb. You have to try to "palm" the bulb into place, which remarkably difficult and almost impossible to do. Very poor thinking on this engineering aspect. You also cannot feel to stems seat while trying to twist the bulb into place. I do all my own home repairs, and have done so for forty years. If I have difficulty, so does everyone else.