JB> something else which iw worth trying is just re-soldering the flyback,
 JB> sometimes the solder cracks...

I'm pretty sure there's a cracked or cold solder joint somewhere.
If I jar the table it will often lose Hsync, and the fix is to slap
the table hard, or sometimes the monitor.  Until the squeal started
I was planning to take it out of service and open it up.  Had to buy
some new soldering iron heaters because the ones I used for years
stopped heating.

... If you don't make waves, you're not underway yet.
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