I had the same thing happen to my TLR-1 that I have had for several years. Called Streamlight and they sent me a new part no questions asked and quickly free of charge. This is a major plus for Streamlight for me.
Another example of excellent Streamlight customer service was when I got into the P320. I found that non of the TLR-1 keys I had made the light fit right on the P320. Called Streamlight and they said not a problem. Sent two brand new parts kits for my TLR-1 and TLR-1HL that included P320 keys free of charge.