Dirt on the inside screen

If lens was cleaned properly, you may have dirt on sensor.

If mark was caused from liquid inside display, you just need to clean the screen from inside, unless it is an LCD.

My question is what kind of dirt are you trying to pick up. Regular dirt does not plug up in twenty minutes. If you see dirt flying around that tells me your vac hose or parts that have a suction is plugged up. Take the hose and hose attachments off and make sure there is no dirt inside.If they are clear check the inside of the vac for dirt as well. Check your filter which is back of the vac bag as it may be plugged as well. The filter should come out to be cleaned.

marks inside the tv glass should only be cleaned by a professional because you may damage the extremely sensitive parts of the television, if its not to bothersome to you , you should ignore it as you will probably be charged an arm and a leg for this,(i know from experience)

you can also try adjusting the picture settings until it becomes less noticeable

If you need further help, I’m available over the phone at https://www.6ya.com/expert/sebastian_77d678f854ac506c

This is a defective LCD display panel. It will cost as much as a new set unless your still within the 1 year warranty. As far as cleaning the screen, you can use an old t-shirt by spraying a little windex on the shirt and wiping gently up and down or left to right but never in a circular pattern. I found it best to do this after the set has been on for 15 minutes to warm up the surface then shut the set off and give a clean.

Monitor wiping cloths. You can get then at any Wal-Mart, Staples, Frye's, etc.

Depends upon what the swipe marks are, exactly.

If they're just residues of whatever she used, then you should try gently wiping the screen down with a clean lint free cloth lightly moistened with a tiny amount of distilled water (the same type used to fill car batteries and steam irons). Re-fold the cloth regularly so that any dirt it picks up does not simply get laid back down elsewhere nor causes scatches. A microfibre cloth is ideal for this as it's also quite effective at lifting silicone wax residues left by many furniture polishes, although it may take a few attempts before the screen is acceptable again.

If the cleaning agent used was abrasive or contained certain solvents then it may have physically damaged the screen. The only cure is to replace the screen but that's rarely cost effective as it's overwhelmingly the single most expensive component of the tv.

If too much pressure was applied then the screen will either recover over a few days or it won't. if it doesn't then your back with the problem of replacing the screen.

In future, never, ever, let ANYONE but yourself dust and if necessary clean the screens of any of your tv's, monitors or similar devices. If you allow them to clean the casings then ensure that they know the correct way to do so (no chemicals, clean slightly dampened cloth ONLY) or do it yourself.

you have to remove the back of the tv to clean the inside screen.

If you wish to get some details; visit the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/
faults & possible causes to LCD & Plasma screen are given with illustrations. You can get an idea about the fault to an extent. Faults to all LCD & Plasma screen are similar,

Your problem is with the blue color,maybe some dirt is sitting on the face of the blue crt and is being projected bigger to the screen,you should try cleaning the face of all 3 tubes,if you familiar with tv service this should help,be careful when removing the back and make sure the set is unplug when you do the cleaning.Let us know how it goes.