I believe you have a 9000 with the optional fan. Hantarex monitors eat flybacks so I would say to replace it. The 4,000 volt focus voltage comes from the flyback and connects to the neckboard/picture tube socket. From what you have described it sure sounds like the flyback is dying. You can buy the flyback and capkit # 802 from Zanen Electronics in Texas. Phone: (806) 829-2780.