You can upgrade to a WBA bill unit, it will take the new 5 and 10, the latest twenty, new fifty, and most older monies and the last 100 prior to the new 100.
you need the following: wba 12 head and transport and bezel, shelf assembly with harness, wba power supply, and a two pin connector and a wba cash can.
hardest part to the conversion is the removal of the old cash can guide , located on the bottom of the metal housing that holds the bill unit. either remove the guide with one screw ( newer machines) or older machines drill out the four tach welds that hold it in place. the metal housing has to be removed from the machine to do this. start to finish ( depending on what tools you have available) 1 hour to 1 and a half.
I have all the parts available to do this conversion.
Jim