i have been playing around with an old crt Rear projection TV... however the image is kind of blocky after it runs for a few mins, my hunch is that the lenses are low on fluid

i have tried cleaning the lenses and the mirror, that really didnt help... open for ideas...

Do you have a tv brand/model? Pictures of the problem? What does "blocky" mean, exactly (more in-depth description of problem)? Anyways, just let us in on some of these and we'll be better equipped to help you with your problem, kind sir.