If you're referring to the original 400 S1 lamps - there use to be a guy on ebay selling them. I also picked up some from one of the electronic supply houses (I think it was Mouser). I don't recall off hand - but think they are 6V. The problem with the ones I bought is they were smaller, not as bright, which may be preferable, but it's a choice.
Here's also the link to the Phasetek site FAQ on lamps:
http://hometown.aol.com/phasetek/faqmeterlamps.html
Here's also the link to the Phasetek site FAQ on lamps:
http://hometown.aol.com/phasetek/faqmeterlamps.html