Marantz VP-12S2 Will Not Light Up

Yes, I looked at the owners manual, and the steady light indicates a bulb failure. With a brand new bulb, it reacted the same way. One problem though, is these aftermarket bulbs can be bad. So no way to test the bulb but to order another one.

Re: this old dog. Well it was a small fortune when I bought it, and I got a 25% discount at the time, but even today its very adequate for the application I am using it for.  

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.