yeah the caps in the crt are cooked.

its up to you wether or not you want to pay to have it fixed...  chances are a replacment is going to start doing it soon anyways. all these old mac and apple monitors need caps.    There are some caps on the MB of the IIgs that need to be replaced as well.  but in this instance i'm pretty sure its the monitor.  the other thing you could do is plug your IIgs into a TV or monitor with composite in, to verify its the monitor.