These were not just a plug and go like they should be. I tried to put them in with no luck 1st, second and third time. I had to file the knobs on the side of the bulb because they didn't quite line up with my grooves they are supposed to twist into. Once I got the first one in, the second one was much easier, but still I had to file both knobs.

WCCC Response:

We are perplexed by your experience.  We have sold hundreds of this bulb and have never heard of someone having that issue.

I really struggled with these bulbs. Comparing them to the old bulbs (which fit perfectly), I found the the location of the alignment pins were off by about 1/32 of an inch which prevented them from being twisted into place. I filed the bulb pins and the notch in the socket and they finally went in.