I recently had the bulb go out on my utility trailer. I couldn't pop the lense off, so I removed the entire assembly. I took to an automotive parts shop and they guy said they don't come apart. I had to buy the entire assembly.... ugg! He said I could break it and try to glue it back, but it probably would not last.
I bought the new assembly, something like $10.00. Popped it back in and working fine ever since.