1. press buttons Set, Menu, Mono Start one by one, followed by up arrow key four times. this should all be done as short a time as possible, around 3 seconds.
2. enter maintenance mode 80 by pressing the up/down arrow key and set key to select numbers 8 and 0
3. press up arrow key several times to get to the Purge* item
4. enter 2, 7, 8 and 3 using arrow/set keys to reset the counter
5. press Stop/Exit key to go to root of maintenance mode
6. enter 9,9 to exit maintenance mode