Three major improvements have been implemented in the MAC 500 and MAC 500 E starting with serial number 4019330001. The first change is a new fixed-gobo wheel with replaceable metal gobos. The standard gobos are the same as those on the original fixed-gobo wheel (P/ N 62325007, Fixed Gobo wheel w/ magnet, MAC 500) so performance is identical with earlier units. The static gobos are the same size as the rotating gobos; the metal gobos may be used in either wheel. Glass gobos, however, are too thick to be used in the new fixed-gobo wheel. Steel gobos are recommended for short-term use only and, if used in the fixed-gobo wheel, may need to be secured with a drop or two of high-temp silicone glue because they are thinner than the stock aluminum gobos.

The second change is that the original color wheel 1 (P/N 62326009, MAC 500 color wheel 1 w/ adaptor, magnet and filters) has been replaced with the same replaceable-filter color wheel as is used in the RoboScan Pro 918 (P/N 62326010, MAC 500/RS 918 color wheel 1 for interchangeable colors, w/ adaptor, magnet and dichroic color filters). The filter layout is identical with earlier wheels so performance is unchanged.

The third change is that the focus lens assembly has been changed to a bayonet-mount system for easier switching between the 17° and 23° options. Qualified technicians can upgrade earlier MAC 500s with the bayonet system by installing P/N 91611019, "MAC 500 bayonet-mount upgrade kit w/ 17° focus lens and 23.5° focus and front lenses." This kit includes both the upgrade to new 17° focus lens and the optional set of 23.5° lenses.

Earlier MAC 500s can be upgraded with the new gobo and color wheel by installing P/N 91611021, "MAC500 II, Effect upgrade kit." Software version 1.7 or higher is required to drive the new wheels because of their increased mass.