Replaced lamp, however 50% of screen continues to turn black when the TV is on a long time.

This problems it is not fixable or worth fixing because of the CRT picture tube of screen itself.Slowly dying,now the tv it is not worth a whole tv anymore if tv require a new CRT picture tube.CRT picture tube,if u can get a hold of it,most likely only can buy it from the tvs corporations themselves only and they charges u like a new tv,because the CRT picture screen it self 90% important to the tv functions itself.