Television and Home Theater

Upon startup, my set picture is full of jagged lines and colors of the program selected. After several minutes--it's getting longer all the time--the picture clears to fairly sharp, except for the top 1/3 of the screen, in which all the vertical lines are 'sawtoot' or wavy lines. The set is two years old; what is the problem?

Can someone tell me what part they think I need for this unit?Symtoms are,picture slowly started to get smaller and bounce up /down.It seemed like when it warmed up picture was getting better but now nothing but sound.model #9p6034c103 magnovox.Thanks

I love my 1985 Zenith Space Command with its space phone, The screan elevates up from inside the base.
The problem im having is that I have sound, but no picture