I bought a 5 watt unit of 6 and they don't fit the base of my lamp. I compared them to my old lamp and they look pretty much the same so I'm trying to figure out what the problem is. I could force one to turn on, but it wouldn't light up. I turned it over and it still won't come on. I put the old bulb back in and it still worked great (just weak which is why I bought these bulbs; double the lumens of my old LED bulb).