I had to mess with one of these today. I recapped it, and noticed it had a brightness pot on one of the daughter boards, just like a 4600 does. I replaced the brightness pot, and was able to get a really good (well... pretty good) picture.
It was kind of neat, because you could see Wells' evolution. The 4600 is a condensed version of this monitor, uses the same daughter board idea, but ditched the audio circuitry, the crazy convergence board, etc.