Please can someone advise on how to fix my monitor. The top half of the
display was fine but the picture then narrowed inwards towards the
bottom. There was also about 1" of black at the bottom, covering part
of the screen (windows) information. After a short time faint
interference lines became apparent with a slight shaking, then the
picture disappeared altogether. The display was better when starting
from cold and gradually got worse over about 4 minutes. I'm guessing
capacitor breakdown, but which one? - any more scientific diagnosis
would be most welcome. Thanks

Check the vertical IC, & polarized capacitors in the area.
The IC wil be numbered like: LA 7835, or TDA ...., or
LA..... Rono.