MR 16 lampholder.

I don't know who's part number you're referring to, but I've had numerous burnouts of MR-16 sockets from a variety of manufacturers. The lamps get really hot, the heat is transferred to the pins, which in turn anneal the socket contacts and destroy the connection

*Same here. If the socket to pin connection is not extremely tight they eventually overheat. I like the look of the MR-16 light, but I always advise against using those types of fixtures. I had one customer who bought over 50 low voltage track lights with MR-16 bulbs. Over a two year period most of them burned out due to poor socket to bulb connections. Fortunately she bought a name brand from a reputable lighting store and the factory replaced every one even though the warranty had expired. The replacements have a much tighter socket and it is difficult to get the bulbs in, but that is how they need to be.