iMac Thin red vertical line halfway on 27" display (Mid 2010)
Has anybody experienced anything similar? The Red line appeared not too long ago - doesn’t go all the way like in other cases I have seen. Red, quite thin just above halfway up - most visible on dark backgrounds, less so on others.
Mid 2010 A1312 (EMC 2390)
2.8 GHz Core i5 (I5-760)
Currently installed High Sierra.
The graphics card is Radeon HD 5750 - has been fine up until this appeared. No line on external display.
Any advice or direction for research is appreciated. Thanks!