The only way to mess with hours on the 21 and 2300 models is to replace the entire B post which is quite costly and most likely has some service record of it being replaced. JFarms
when i installed a tailings monitor in my 2188 i got a new chip with the kit and all the hour dropped back to zero. If you kept the old chip and put back in the hours would go back to what they were before the chip was put in. But the tailings monitor would stop functioning.