Well...I'll acknowledge the possibility that the bulb in my NuArc NL22-8C is at the end of its life. It's the bulb that came with it when I bought it used, and I have no idea how many hours it has on it. I have a replacement, but in an attempt to protect the upper safety glass from shifting / breaking since it gets moved a lot (don't ask), I added nuts to the locating studs. Problem is, now I have a big dis-assembly project to get at the lamp assembly. Don't know why I didn't replace the lamp when I had it all apart...

--Greg