I gave up on it. An Epson 3880 was delivered to me today. It won't print as large. but I think its prints will be large enough for me. It seems better designed for the hobby user than do the Canon iPF's. It sounds like you were a very light user of the printer, like I was, and all the evidence seems to suggest that light use is really bad for these machines. The 2618 error message indicates a failure of the power supply board. I finally got a head check to run and one set of light magenta patterns was completely gone, suggesting a head failure as well. Adding together the cost of a new power supply board, a new head and the probable service costs led me to conclude it was throwing money down the rat hole. I got a refurb 3880 for $930, free shipping and no tax.
The iPF6400 has a different part number for the power supply board which may suggest that was a frequent failure point with the 6300. The 6400 allows use of larger ink cartidges, but otherwise is basically the same printer.
If any one still has a living 6300, I listed some unused and unopened ink cartridges in the For Sale section of the forum for what I think is a decent price.