To really clean the epson 7600, alternately print a nozzle check and then run a cleaning. Do this 8 times in a row. If that does not fix the problem, it could be that you need to replace the cleaning assembly. You could also try just cleaning off the wiper blade in the cleaning assembly. You need to remove the left side cover to get at the wiper.
Here is a link for the service manual SP76-9600_service manual.pdf
I'm only including this for the instructions on removing the side panel, and for recognition of the wiper blade.
You can do your own cleaning assembly replacement if you have any sort of experience in that sort of thing, But if you don't, I would recommend leaving that to a tech. (But it is pricey.)