Canon L80 service manual

First, try changing some Document Feed Rollers etc.

FC8-9251-000 is the pickup roller
FL3-1023-000 is the separation pad FM3-8679-000 is the feed roller

That would fix 80% of the problems you may encounter

Whit
Item, Inc.

If you have time and small amount of skills do the next:

Open cover of keyboard panel ( pull towards ), then you will be able to see, on fax side two rollers, and on keyboard side one separation assy ( rubber piece grey or black color ), as first aid use mild sand paper and "scratch" on it and clean with alcohol.
Also clean the rollers on fax side, while turning them.

This is only as first aid. If then works, that means that you need to order and replace separation assy. For EU code is HG5-1308-000.

TIP: when you replace sep.assy, also tighten the spring wich holds separation assy.

You need to clean/replace paper feed rollers and separation assy.

Again a two fold possibilty(no pun intended)!!
There is a lever on these models located on the left side of where your transmitted documents feed in. It has two icons. One icon is for a single document and the other is for multiple documents. The Normal setting is the multiple document setting.
The single document setting is an indication for ( believe it or not) sending hard card or cardboard. If you have set this unit to this setting it will swallow the entire pile at once.
Now then possiblity #2.. and a very common occurrance!
This document feeder has a very small piece of rubber that is called
"The separation pad". If you were to pull open the feeder area and notice the 2 inch wide black roller. Exactly opposite from the black roller on the opened cover you will see the separation pad.
Here's what happens. The sep pad rubber gets old and hard. As it dries out it becomes shiney and looses it's ability to Hold Back the next page. Ergo........ Double feeding occurs.
Folks this part is cheap cheap cheap. Don't live with this problem. Find a parts resource for your unit and get a new sep pad.
I have seen these machines at our local land fill and for $1.10 I repaired them good as new.
Now practice safe Fax !!!

It's actually heat and pressure, that 'melts" the toner to the page, and what is happening in your case, is that the pressure roller is worn out, so you're not getting the contact between the heat and pressure rollers necessary to properly adhere the toner. This will require a service tech should you want to spend the money to repair it.

There is a separation pad under the feed roller,that pad needs to be cleaned or replaced.If you open the fax and remove the cartridge,inside at the back were the cartidge was you will find a roller,cleen that roller.Under the roller there is a strip of rubber-the separation pad.Take a ruller cover it with a cloth and use it to clean the sep assembly under the roller.If the problem pressist the sepparation needs to be replaced.

you mean you're getting 1 or 2 extra sheets when machine is printing faxes? Feed roller and separation pad that pull paper from the tray are worn.....cleaning will help in the short term.

Your fax machine probably has what is known as a "separation pad". This is a part near the rubber roller thst starts the blank paper on its way through the machine. It is supposed to let only one sheet through at a time but when it's surface wears, it doesn't function properly. A service technician is needed to replace the part.

it makes it a lot easier if you change everything and know it's good for years.

here is the manual

http://www.usa.canon.com/app/pdf/copier/L80_SoftwareGuide.pdf

Still a problem? Can you be more specific?