[Jeffhs]

My RCA CTC185 table set fell off its stand last year, and I found the same color problems (splotches, like purity issues) when I fired it up again. I was able to get rid of the color splotches by running a magnet from an old loudspeaker around the screen, with the set off. The color distortions disappeared and the picture has been excellent ever since.

I agree with Andy that the CRT in your set may have been damaged when the TV hit the floor, but I'd try his suggestion to check the yoke positioning first. I will say, however, that it was fortunate the CRT did not implode or the set did not suffer further, more serious damage.