Explain this!

[Aquattro]

Bob, the bulb is not in contact with the cap. And this particular bulb has been in use for almost a year with no problems. The other side is fine. The cap also has a distinct burnt smell, which I don't think would exist if it just melted from heat. I really have no idea though, so you could be right. I haven't read that thread about arcing yet, so maybe something there will help.