Lemme preface this with the fact that I am still learning how to fix issues on CRTs. I have had a few wins, but I have this unit and 2 Sanwa's that I still haven't gotten working yet.
Anyways I have a Nanao MS9-29A in a Taito Battle Gear 2, It went to a black screen and was making a squealing noise. Pulled the chassis and pulled out the HOT and found that it was shorted. So I ordered some new ones, checked around the board for anything else that stood out (shorts, etc). Put the new HOT in and fixed up the cruddy looking solder joints on string of surface mount resistors under the board near the flyback. It fired right up, the picture looked great, I let it run for a bit and after about an hour I found it with a blank screen and squealing again, so I guess the new HOT failed.
So now I need to figure out what else is out of spec or bad that would have caused the HOT to fail.
I'm open to all suggestions/information, I'm also working on speaking with a friend that is significantly more versed than I am with CRTs when he's not busy.