This may be a build up of dirt Etc causing the spark gaps to discharge at a
lower voltage. All color sets, monitors and TV,s have spark gap capacitors
which are designed to discharge should the hi voltage go too high. Also,the
hi voltage regulator could becoming erratic due to degradation of circuit
components. Also, dirt build up in and around the hi Volt transformer (
Flyback) can impede the circulation of air in that area causing the
temperature of components in that are to increase.The higher temps could
change the operating characteristics of any semi conductors in that
area(transistors,diodes,etc) causing what is known as thermal runaway or
unstability.
If you are handy at working on this type of product or have a friend who
is,you could:
1. Disconnect the monitor.
2. Remove the back.
3. Note the wire connected to the picture tube(crt), it is usually red or
blk and has a large rubber suction cup looking thing at the end where it
connects to the crt. KEEP YOUR FINGERS AWAY FROM THIS AREA,HI VOLTAGE.
4.Inspect the innards for a build up of dirt and dust paying particular
attention to the area around the flyback transformer. Usually located near
the right rear area of the main circuit board.
5.Excessive dirt and dust may be removed by carefully using a vacuum clnr
and/or a clean, soft paint brush.
6.Replace the cover and fire it up. It may snap crackle and pop for a few
seconds which is normal.If it was dirt causing the problem, this usually
takes care of it.
7. If the problem persists, a circuit component is probably breaking down
and will require service by a shop.Cost $50 to $75 and up.

I have been a video/TV Tech for over 40 yrs and have repaired many hundreds
of sets following this procedure.

Good Luck,
John Dinges

         PCBUILD maintains hundreds of useful files for download
                     visit our download web page at:
                  http://freepctech.com/downloads.shtml