Picture has a yellow tint. It's from an old video game that ran over 12 hours a day. Has new bulb. Except for the yellow, works fine.

Hello there:
The best way to describe this is what is called screen burn in.
this is very common on screns that have games or pictures that arre displayed for long periods of time without being shut down just like on a computer screen when a screen saver is not used .
there is nothing wrong with the bulb.
the yellow that you are seeing is actually burned into the glass part of the projector and the lense
so if you can and feel like you can dissasemble the projector dissassemble it and locate the glass and see if you can get the yellow tint that will be on the glass and the lense off by using some rubbing alcohol and a cottomn swab
But if it wont come off you will have to replace the lense and the glass ok
Hope this is very helpful for you
Best regards Michael