The UV light destroys these sockets after 4-5 years. They become weak & brittle and break easily.
When changing them, use a small screwdriver in the slot next to the wire on the socket - it releases the wire and lets you easily remove it. When installing, the wire is just a push in.
If you are reading this - you probably have the same problem - why Lennox would use a plastic that deteriorates with UV light to hold UV light bulbs is beyond me! I bought these and easily replaced the sockets in my existing unit - bulbs mount effortlessly now! I thought about covering the new sockets with electrical tape to protect them from the light - but wasn't sure about the heat in there... NOTE: the wire is held by friction - just use a pliers and pull the wire out of the old one - will slide right into the new one easily.