Our company just purchased a print shop with 2 Riso's and both are misreading the toner levels. The current toner tube has less than a 1/4 toner used, but the display is showing, that 3/4 toner of the toner has been used. The last duplicator, that I worked on was a Duplo, and that was 15 years or more ago, so any help would be appreciated.