You'll have to read the manual re the various light conditions. One light condition could indicate various things, not just one possible problem.
Those were good projectors. The problem with the most modern DLP units, is they have sacrificed pixel density for contrast. Contrast requires the larger chip sizes (with spacing between pixels, etc, long story) and the matching optics to go with them. the $1-2-4k value for the lenses on some of them (of the era), really pays off, in the end.
So, oddly enough, that era of projectors can have and generally does have more 'real contrast' than a 4k single chip DLP of 2019 build.
Those were good projectors. The problem with the most modern DLP units, is they have sacrificed pixel density for contrast. Contrast requires the larger chip sizes (with spacing between pixels, etc, long story) and the matching optics to go with them. the $1-2-4k value for the lenses on some of them (of the era), really pays off, in the end.
So, oddly enough, that era of projectors can have and generally does have more 'real contrast' than a 4k single chip DLP of 2019 build.