Thanks for posting on the community and I'm sorry to learn you're experiencing issues with your picture.
Since you have already rebooted and replaced cables then I would like to arrange for one of our engineers to take a look at this for you.
I'm just going to send you a private message with appointment times which you will find if you click on the purple envelope at the top right of the screen.
Speak to you soon.
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Welcome to the community and I'm sorry to hear you're also experiencing this issue.
Can I just confirm whether the cables are secure at the back of the box and whether a mains reboot has made any difference please?
I may need to arrange for a technician to take a look at this so please let me know if you're still experiencing problems with the picture.
Looking forward to hearing from you