Apple IIgs color monitor

[Alberto Cavalcoli <acavalcoli@racine.ra.it>]

I'm sorry if anyone have posted this question before.
I have a problem with my Apple IIgs RGB Color monitor: after 30 mins of
works the monitor become too brightness and lost focus. I have tried to
replace all the electrolytic capacitors and two big resistors (R413 -
470 ohm, R901-6,8 Ohm), but the monitor do not show any signs of getting
better.
Have anyone fixed this defect ?

Many thanks in advance