O.K. when you said tube swap, did you also take the yoke off? Yokes have to be tuned to the tube they're on, if they're too far up or back the neck all your colors will be scrwed up. Same thing with the convergence rings. If they're not right where they're supposed to be your colors will be off.
Also do you know if the tube was looking good in something else? Also the monitor chassis, was it looking good on the old, burnt tube?
If the red images don't light up, but the whole tube looks red, that sounds like the monitor chassis to me. If your signal isnt' getting through to the gun because you've got a bad transistor somewhere, the pots on the neckboard will turn up the red on the background but nothing that needs to be red will be.