First off...that TR4 is GORGEOUS. One of my all time faves...miss my old one alot. The Sanitronic 80 was a great find. I've got a couple myself. Love these, and they're great cleaners. Run forever, too. Bulb can be found at the automotive shops. It's basically a taillight replacement bulb, bayonet type which you push in and turn. I *think* they are 12w J6...but I need to verify that.