PIXMA MP780 purge unit

[ghwellsjr]

I am in the process of repairing an MP780, and I think I need to clean the purge unit. My problem is that I can't find any directions as to how to do it. I don't want to cause any more harm than necessary. Anybody out there know the procedure to clean the purge unit on this machine?
Thanks

This is a very old thread and I'm sure stuber has either solved his problem or given up. He did post his question one more time here, but again with no one answering his question: How do you clean the purge unit?

First, I want to provide an easy test to see if the purge unit is clogged:
Do a nozzle check.
Open the cover and wait for the carriage to stop in the middle of the printer.
Take a flashlight and look for the two purge pads off to the right where the print head parks.
Use a syringe, eye dropper or pinched straw to put some Windex or other window cleaner or just plain water on the two pads.
Close the cover of the printer for about 15 seconds (until the noise stops).
Open the cover and look at the two pads. Do they show liquid on them or are do they have a coarse surface?

If the liquid is still present, you have a clog in your purge unit.

The clog may just be in the purge pad itself. You can remove it and soak it in Windex for an hour, then rinse it off. You should be able to suck air through it. When you re-install it, the notch in one corner goes to the rear left side of the printer.

If that doesn't clear up the problem, my experience with clogged purge units is that the clog is not actually in the purge pump but rather in the tube coming from the bottom of the purge unit to the entrance of the peristaltic pump. I have been unable to unclog this tubing from the top of the purge unit. It required me to take apart the printer and get to the other end of the same tubing and squirt some Windex into it. The process for dismantiling the printer is the same as for changing the waste ink absorber pads. You can read about it here.