No picture. NEI 28" Nicam Stereo Television C28F1FXN circa 1995. No picture - all other

Question

NEI 28" Nicam Stereo Television C28F1FXN circa 1995. No picture - all other functions perfect. CRT board heater voltage reading at 13Volts AC relative to adjacent ground connection, nearby 200V DC connection fed by same ribbon cable is ok. No visible dry joints, heaters glow but not very brightly. As far as I can see LOPTX provides output to CRT board heaters. ADDITIONAL SYMPTOMS RECEIVED ON 3/1/97: When the LOPTX screen output is increased, a dark blue line across the middle of the raster is observed - looks a little like field collapse. Suspecting colour decoding chip. NB I think the heaters are ok after all.