Just an idea.......
Sometimes the O-ring on the bulb is the issue. Dry, it seems to not want to allow the bulb to slide into the hole in the housing, but if you put a little white grease on the O-ring, it slips in super easy. However, if you get ANYTHING on the bulb glass, (fingerprints, white grease),you will get to perform the bulb replacement again sooner than you really want to.
YMMV
Ken R955