Printers that are used for MICR printing must have

Printers that are used for MICR printing must have a unique MICR font that is modified to suit the unique printer engine, and it must be modified to the pixel level to match the magnetic toner provided for that printer. This is essential to ensure the correct waveform, dimension, and signal strength when a check is printed with the correct MICR characters. In addition, the MICR font must meet ABA-X9 standards to ensure acceptance of your checks by banking institutions.
The magnetic MICR toner that you choose must be specifically designed for the particular print engine in the printer. Ensure the toner has been thoroughly tested for consistent signal readings, image permanence and uniformity, and excellent edge acuity. Toner coverage must be solid with no extraneous toner lay down.
OEM cartridges are always a safe (but more expensive) bet. If you buy a "compatible" brand, ensure it has a new OPC drum, new primary charge rollers (PCRs), a new black velvet magnetic sleeve, and new image wiper blades. The hopper system must be filled with high-quality, low-abrasion MICR toner.