rca model#25gt505 chassis#167e

Problem with the set is that it goes into high valtage shutdown. I disengaged the shutdown circuit so that the set can turn on.With the set operating i have sound but no brightness, turning up the screen voltage all the way i have a dim raster.All the d.c. voltage from the power supplies are normal.I subsituted another chassis and the crt and yoke check out ok.I beleave the problem is the flyback transformer being an expensive part the customer will not go for repair. Has any one out there have this problem with this model? I may be missing something.