Check the mist multi-ball driver board (under the PF - incorrectly called "24 opto board") - correct name "24 INCH opto board"

There is a small green choke on the board that has very fragile legs - you might be lucky and be able ro re-connect it if it is fractured?

This board can cause all sorts of weird ball search and multi board  and opto problems with BSD.

http://www.homepin.com/bsd.html