Shadowing

Have you tryed to adjust the on board convergence yet?? it sounds like the blue horizontal could have shifted. Put the aset in test mode and adj befopre taking set to servicer. Good luck.

If still under warranty or if you have no electronic repair experience you should take the set back to the shop or to a repair person. Some of the solutions described below can be dangerous, TV's are very hazardous to service. Even when plugged out, TV's can store very high voltages.

Looks like a picture tube problem.
Try to reduce the contrast, maybe it will be better.

Look into the three tubes while the TV is running, and observe the
picture quality of the three. If the red and green are crisper and clearer, and the blue's all hazy from bacteria growing in the coolant, then the fluid needs to be replaced. The CRTs of the colors that seem hazy need to be removed from the light box to be
serviced. The coolant needs to be drained, the CRT assemblies
disassembled and totally scrubbed clean and refilled, then reinstalled and converged. If the coolant is
clear, it can be a weak CRT.

Also the convergence STK ships might need to be replaced, and the soldering checked.

Good luck