Mysterious black lines when printing- help?

I have a Canon Pixma MP760 printer/copier/scanner​. I just printed a picture of my dog, who has a substanitial amount of black hair, and I noticed a series of "dull" black lines in the areas where the dog's hair is black. The lines are straight and uniform, about a quarter of an inch apart, and they only appear where there is black content in the photo. That is, if you follow the line and it runs into a colored area, it disappears.

I'm using high quality glossy Canon paper,(8 1/2 X 11). Just to be totally clear (I hope) the "lines" I'm talking about are actually dull lines appearing within glossy black areas -- they're not so much actual lines as they are long thin dull areas. I've printed through Canons Digital Photo Professional software.

Does anyone have an idea as to if I might be doing something wrong? Is this (quite noticible at the right angle against the light) imperfection to be expected with a relatively inexpensive multi-function printer?

Any thoughts would be much appreciated.

Have you cleaned your print heads latley? I'm sure your canon printer software allows you to do this.

Thanks for that idea. The printer is seveal years (4?) old, and I haven't done anything other than change the ink cartridges. I presume that changing the cartiridges doesn't "clean the heads." I had no idea maintenance like that was required. Is that something I can do myself?

Yeah, inside the printer driver.. under advanced there is a maintenance tab. You can do several things inside there. I would do them all.. heads.. theres also one to clean the rollers as well with a blank sheet of paper..

Thanks RonUSMC and Shybull. I'll give it a go.

I spend half of my time rejoicing about how incredible the machines we have at our disposal are, and the other half completely frustrated at how much you have to know to work well with them.

So it goes . . .

The answer lies in the software package you are using. I had exactly the same probelm when printing direct from Photoshop Elements 6.0.

Having tried every maintenance function possible on the printer, all to no avail, I then tried printing the same photo from Picasa 3 and it came out perfect. I'll now spend a bit of time trying to find out if there are any fixed for Photoshop Elements 6.0............if I can't find one, no matter Picasa is as good as anything for basic work and if necessary you can do all the trickery in Photoshop, save the image, then print it from Picasa.

[QUOTE=sawdrl;6933089]​The answer lies in the software package you are using.

Thanks Sawdrl,

I did do the maintenance procedures as previously suggested, but the pre-testing showed that there were no maintenance problems. Flailing around I tried printing from Canon's Easy Photo Print (if that's its correct name), and the photo came out perfectly. I didn't go back and see if printing from my Photoshop Elements 3.0, which I had originally used, was cleared up because I didn't want to waste photo paper, but your comment furthers my belief that this may have been the problem all along.

It does seem odd though, doesn't it?