The paper printed by the printer has suddenly become very dirty. The printer is seldom used.

No has nothing t do with dirty heads or nozzles. I think you used the wrong paper (or plastic) and did not tell the printer what it was printing on. Be aware ink yet printers need special paper, so the droplets (how small they may look with only a few pico litre) don't give a splash pattern and the ink will dry very quick. What looks like normal paper, has an absorbent on top of it. Only use photo paper when it says photo paper for ink yet printers. The best results you get, when you use the Canon paper, canon ink and use this in the settings while printing.

If your printer jams paper every time you try to print then there are two options, either the paper you use is wet (higher percentage of dew easily piles up if you have the paper boxed out for a while) or the paper is thin (usually the standard printer paper is 80 grams per square meter, if you use thinner paper it can get clogged because it can't get passed on from the intake rollers onto the ejection rollers.
The second option is that your printer's rolling mechanism is dirty/greasy. You'll need to open up the printer by lifting up the cover as when you're replacing the cartridges, and wipe the rollers with a dry cloth. You may need to do this several times before the rollers have enough friction to be able to pull the paper out and eject it onto the tray for printed paper.

Sounds like the paper feed roller is either worn or dirty. It is located in the back of the printer just above the paper tray. Try to wipe it clean with a damp cloth to see if that help.

Clean your Rubber Spooler inside the Printer which had become dirty .
Possiblity of Damaged Catridge

Inside of the machine is dirty.
If the inside of the machine is dirty, the printed paper may be smudged.
Follow the steps described below to clean the inside of the machine.
1. Ensure that the machine is turned on and there is no paper loaded in the Auto Sheet Feeder.
2. Place A4/Letter-sized plain paper in landscape orientation, horizontally fold it in half.
3. Unfold the paper, and load the paper in the Auto Sheet Feeder with the inverted-V edge down.

4. Select <Bottom plate cleaning> from <Maintenance>.
5. Select <Yes> on the Bottom plate cleaning confirmation screen and then press [OK].
Paper will be ejected.
If protrusions inside the machine are stained, wipe ink off the protrusions using a swab or such like.
* Important
Before cleaning, be sure to turn OFF the machine.
Paper feed roller is dirty.
Follow the steps described below to clean the paper feed rollers.
1. Ensure that the machine is turned ON and there is no paper loaded in the machine.
2. Select <Roller cleaning> from <Maintenance>.
3. Select <Yes> on the Roller cleaning confirmation screen and then press [OK].
The paper feed roller will rotate as it cleans.
4. Repeat this operation twice.
5. Load three or more sheets of A4/Letter-sized plain paper lengthways in the Auto Sheet Feeder.
6. Select <Roller cleaning> from <Maintenance>.
7. Select <Yes> on the Roller cleaning confirmation screen and then press [OK].
The paper that is loaded in the machine will feed through the machine and be ejected.
8. Repeat Steps 5 to 7 three times.
Inappropriate paper type is used.
Check to see if the paper you are printing on is too thick. See Paper Types You Cannot Use.
Note that smudging may occur at the top and bottom edges of the paper when using Borderless Printing. Ensure that the paper you are using is compatible with Borderless Printing.
Thick paper is used.
When printing on thick paper, set the Paper Thickness Lever to the right.
This widens the gap between the FINE Cartridge and the paper. Try this maneuver if the printed surface is scratched.
Media is curled.
If all four corners or the printing surface of the paper is curled, the paper may become dirty or may not feed properly. Use the paper after correcting paper curl as follows.
1. Place the printing surface face up (A), and cover it with a sheet of non-printing regular paper to avoid damaging the surface.
2. Roll up the paper in the direction opposite to the paper curl as per the figure below.
3. Check the printing paper to confirm if the paper curl is eliminated to within approximately 2 to 5mm / 0.08 to 0.2 in (B).
It is recommended to print on curl-corrected paper one sheet at a time.
The media type is not selected correctly in the printer driver.
On the [Main] tab of the printer driver, ensure that the [Media Type] selected matches the paper loaded.

In the [Print] dialog box of the printer driver, select [Quality & Media] from the pop-up menu, and then ensure that the [Media Type] selected matches the paper loaded.
Paper is loaded incorrectly.
Load in the portrait orientation regardless of the print direction of the Auto Sheet Feeder.
Ensure that paper is loaded correctly. Slide the paper guides against the paper stack.

TRY CLEANING THE DRUM...

there is a part we could it mask its piece of metal in front of the head clean if the problem dos not solved tray to change

Sounds like you've got dirty rollers or paper chips stuck in the rollers. You'll have to inspect and remove what you find. You may use a rag with rubbing alcohol to clean rollers that have become glazed with whatever they get glazed with...dried ink and such.