Tube Video Problems
 

When I first bought my Zenith TV i watched it for 3 days with a very nice picture.Then on the 4th day the entire screen turned red and purpleish color for a few seconds. Then everything went very dark like the brightness was turned down. I turned the TV off then back on. The picture showed normal but was slightly less clearer than before and redish looking. I had the TV Tech come check it out. He took the back off and taped on the "tube cone?" with a wrench and moved a switch like lever that was attached to it. He didnt really give a good explanation as to what happened, but since then the picture never was as good as the first 3 days of use. Any reason or explanation as to what happened? Thanks