Can't print PostScript files to a PostScript printer using Red Hat Enterprise Linux

Issue

• A printer (Xerox WorkCentre 7228) was replaced by another printer (Xerox WorkCentre 7120). Using system-config-printer the relevant ppd file was activated.
• Xerox WorkCentre 7228 worked. Xerox WorCentre 7120 doesn't.
• PostScript files won't print to a PostScript printer. Other types (text, PDF) print fine.