Replace printer cable is one thing.
It may be the wrong printer is selected on the iSeries Access session. Bring up the printer session and then go to the File menu and then select Printer Setup and insure the correct printer is selected. If you are using Host Print Transformation you may need to check that the correct printer model is selected in the configuration setting. You should check this web site to select the correct printer model.
I refer to this site anytime I setup a new printer.
Since it has been working and now stopped I would check the settings on the printer. It could be that the emulation setting was altered.
Maybe something in the printer setup was not saved or has been changed. Check the whole setup to see if it all makes sense: www.qsecofr.ca/printers/printers_files/Page286.html