I ended up doing pretty much what was mentioned above for the DS that was giving me problems.
If you look at the LUX there are (3) tabs: (1) larger size tab with a ramp on one side, (1) larger tab with straight sides, & (1) smaller tab with a ramp.
On my car, after looking how the other lights were oriented when they came out - the smaller tab with the ramp needed to be at the 12 o'clock position when inserted prior to turning clockwise (when looking at the light from the rear - turn to left when looking at front of car).
Seems to me that the o-ring design seal was giving me problems getting the light to seat fully in before turning. My old style Lux had a different type of 'flap' rubber seal (as well as the myriad of halogen bulbs that I have tried).
I also ended up using a small bladed screwdriver in one of the slots of the cooling ribs on the body to push the light into the housing, then used another screwdriver against the notches in the light body to turn the light to lock.
I got the PS to go right in just by hand.
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