Well my LS-4 has been "bouncing around" in my work area for the past 6 or 7 years (since the last bulb replacement). Although I am sure it has nowhere near 5000 hours under its belt, I have lately felt that it really doesn't illuminate the subject or the mind as it should. In particular, it is hard, even on a 6-panel booklet pane, to get an even fluorescent exposure. Perhaps bicolor is correct in saying that 4 watts just doesn't cut it. RayTech also has a 7 watt model. Do you think this would be a major improvement? I looked at the link to the eBay
search you provided but that seemed mainly for sterilization and other non-philatelic uses. I would like to have a lamp which can work on both short and longwave ranges individually and at the same time.