Thanks for your thoughts. My shop is well aware of the need to not touch the bulbs and how to clean them; I believe they use latex or similar gloves. They’ve checked the charging system and never found a problem. I bought Sylvania bulbs once, at a high price, and they burned out just as quickly. Funny, the stock bulbs lasted a long time,although I did have one replaced under the 4yr/50,000 mile warranty. This intermittent but persistent problem is about to drive me bonkers!