inkoholic said:
So the white stripes on my nozzle check print (see previous page) could also be caused by electrical issues? This thing is getting more complicated :/

I don't want to mess up my brother's printer as well. Don't really know what to do now: repair my MP610 and risk spending a lot of money, or ditch the 610 (which is still working OK but not great) and get a new printer. I could get an MG5150, or an HP Officejet 8500 (seems to have the lowest OEM ink costs by far).
If you want to keep your MP610 running, then there are a few things you can try.
1) Buy new OEM Canon cartridges to replace the problem cartridges from your nozzle check. Alternatively, you could take your cartridges and put them in the other printer you mentioned to see if they work without issues. No harm should occur from cartridge swapping -- unless you let the printer print without ink in the print head, which would cause print head failure. From your abbreviated nozzle check images, I don't see complete ink starvation yet, so you should be safe for this test procedure. The idea is to isolate the problem(s). This test will help determine if the cartridges are wholly or partially at fault.
2) You can try one or more of the various methods found on the forum for unclogging the print head. Time and patience are virtues here. Cost is negligible.
3) For completeness, you can test the purge system, though I doubt it is your problem. Use Windex with Ammonium D, isopropyl alcohol, or water to fllood the purge pads. These pads are seen to the extreme right when you look into the printer. The print head parks above the pads when the printer is idle or off. When you open the lid the print head moves to the center and parks for several minutes. Using a flashlight and needle and syringe, or other suitable device, flood both purge pads until fluid pools, then close the lid and do a cleaning cycle. Then open the lid and look to see if the pooled fluid is gone or not. If gone, you might even notice one or both pads to seem a little bit "whiter". Report back your experience and findings. Caveat - the print head parks in the middle for only several minutes. Maybe the first time you try this procedure you should pull the electrical plug once the print head parks in the middle to give yourself ample time to complete the task comfortably.
4) Whenever I see straight lines like yours on a nozzle check, I lean towards print head malfunction rather than clog. Nature doesn't do perfect straight lines. Clogs aren't usually perfectly spaced to cause such straight interspersed decreased ink output bands. But you never can be sure, so we try unclogging sometimes before spending $50 plus on a new print head. Then again, sometimes you just get the new print head and be done with it.
5) I doubt this is a problem with any other part of the printer, but stranger things have happened.
Let us know what happens.