I would have to agree with everyone esle pick up a new monitor. 19" LCD is a really cheap now, used working one even cheaper.
If you just do not have the funds. You can try adjusting using the on screen tools to see if adjusting them to correct it.
You can pull off the outer casing and adjust the tubes, small should have paint glue to hold the adjustments in place. I do not suggest doing this if you are not experience in CRT monitors and repair. There are some very high voltage components that can injure you and kill you if incorrectly discharged.
-John