Client uses obsolete DOS-based app (ProfessionalFile) on old Windows XP machine. Prints 2-part checks on dot matrix printer. The Oki ML420 was purchased as a new replacement 2-3 mos. ago. Rebuilt the ProfessionalFile database using FileMaker Pro 11 and loaded on iMac with OS x 10.6 (Snow Leopard). Oki provides drivers for DOS, Windows, NT, and Linux, but not Mac. OS X ships with a CUPS driver for Oki 9-pin printer.
The check formats correctly in Preview, and prints correctly on HP OfficeJet. When I try to print to Oki, I get a single line resembling a bar code, and the printer appears to seize up from buffer overflow - no error, so that's a guess. The printer will repeat the action from the iMac, but requires power-cycle before it will print from the PC.