About Sony Multiscan 20 sf II

Hi There,

I have a problem to solve. I have Sony Multiscan 20 sf II (CPD-20sf2T) 20" CRT Monitor. when I switch it on (in Cold start) a black line (about 1/2" ) appear(vertically) in the left side of the screen. (actually the picture size is reduced). after a half an hour (when the monitor is getting warm) the picture size is getting normal gradually. This is happening every time I turn ON the monitor in cold state. after it's warm, it's OK.
and my monitor has a convergence problem(the convergence is not properly setted, I mean when I set correctly the top convergence, the bottom convergence gets out of focus (very little) and vice versa).

what should I do for this. Can't I repair it. if it is possible, where the fault is existing. (I have electronic knowladge).

Please don't care about my wrong English.

Thank you,
Nimesha Silva