MP780 Maintenance Cailbration not working

Not normally but the black print head nozzles maybe blocked.
Inkjet printers need to be used frequently to prevent ink drying out and blocking the print head nozzles.
If the print head cleaning maintenance routine does not clear the blockages, then print head needs replacing, but it may be expensive.
It may be more cost effective to buy a later model and better printer than replace the print head.

It's time to replace either PRINT HEAD or PURGE UNIT.

you may have a blocked printhead, try running a clean from the printers own maintenance program
good luck

This simply means that black ink is installed but not CHARGED properly. What you see in a color printing has actually no black color in it but a combination of the hues of blue and yellow and magenta; though it appears black or dark.

Now, use your printer's maintenance utility to do Head Cleaning. To do this, click Start => Settings => open your Printer and Faxes, then right click on your printer's name. Then click on Printing Preferences. Now in the window that opens, click the Maintenance tab and do Head Cleaning. (In some printers, maintenance is called Toolbox)

Your best bet is to reinstall all of the drivers. You can download them from this link for the MP780:

http://software.canon-europe.com/products/0010139.asp

Your paper feed source is wrong .Go to the printers control panel and change the feed source.
If all you do is 8.5X11 you can go into the maintenance tab and choose it to automatically change paper trays by selectin auto continuous feed.Make sure paper is in both trays of the same type and size.You will hear the printer try and grab the paper three times then it will automatically switch to the next tray.

my printer keep saying paper jammed but there nopaper jammd in there.

PIXMA MP780 "WRONG CARTRIDGE" MESSAGE?
Here is what I did and it now works just fine.I turned off the printer and unplugged the power cord, and unplugged it from my computer. I then removed all the ink cartriges and removed the print Head I got some rubbing alcohol put it on some toilet paper and wiped down the back and bottom of the print head.Plugged everything back in and It now works better then ever.

## 357 error is the ASF paper feed position error on the MP780.
I have the maintenance manual in pdf format I could email you, its a 5.6Mb file be warned :)
regards Paul
[email protected]

sometimes those measures of ink levels are not very accurate. actually they're usually rather far off... try a new cartridge Usually the easiest solution.