Are you using an EPSON original cartridges or an OEM cartridge in your CX6600?
For original cartridge of magenta, you can choose another paper and test again.
But for a compatible cartridge of magenta, I think it would be better to change another brand of cartridge.
If you are using a CIS for...
I think the R240(USA)/R250(ASIA) and R320/R340(ASIA) are designed intended to thwart refilling, CIS installation. see picture http://www.sinopis.com/forum/forum_posts.asp?TID=10&PN=1
Only this model ATUO RESET CHIPS can be used on R240/R340, see picture...
Canon uses the chipped carts on the new model of ip4200, and I have test it, and also i have studied its ink (8BK,5PGBK,8C,8M,8Y), I think we still can work with the refilled carts of ip4200 although its ink monitor disabled.
By now i use my own inks on ip4200, it is a good printer.
I think the printer head had broken by you.
"injected alcohol into the nipples that are attached to the head ....Received a spray of alcohol when injected. "
this is not the correct operation.
I think the correct method is "dipped the head by speacial clean liquid" .
Now you have to give up...