Mita DC-3060 Sorter Setting Problems

The sorter AS2120 on a Mita DC-3060 copier keeps coming up with a reset sorter message on te display. The only way we can get the message to go out is to open the door on the side where the stapler is located and shut it, and after that the code goes away. We replaced the sorter switch that lets the copier knows it is set. It is located on the back of the sorter and pushes against the copier. We also tried swapping out main boards on the sorter but that didn't work. I was just wondering there is a problem I am over looking or do these type of sorters have problems?
Any help appreciated, thank you.

[copygirl]

There is a small pcb underneath the sorter that has trouble in the past. The diode is not strong enough. It reads thru to a sensor on the top end. You'll have to get under sorter and there is a small cover. Just take that off and you'll see what I'm talking about. If you need the specs on the diode I'll see if I can find it. We don't have that many in the field anymore but I remember just going to Radio Shack and getting one. It would be easy and cheap to try. Let me know if I can look up anything for you.