After first turning the computer

After first turning the computer on, the monitor screen image will sometimes display: off center vertically or horizontally, tinted off color, as lines, or not present at all. SOMETIMES pushing the monitor power on-off switch will produce the corect image. When this fails, disconnecting the power plug and reconnecting it once or sometimes several times will produce correct image so screen is fine and useable after the fussing with the tweaking proceedures described. I have tried changing the monitor cable...no change. This acts like some sort of signal variation at start up and I am wondering if that or whatever is causing the problem is fixable at reasonable cost. Monitor is a Sony SDM-HS73 LCD 17 Inch which I especially like and has no other problems meaning I would spend a moderate amount for repair or repair myself if it needs a part replacement and part is availab;le.