To recover a hung topbox motor:

0) exit real time system if still around
1) exit guider program (click on Quit in vidDisp and CTRL-C in the xterm)
2) find the jumper cable in the 1.2m cabinet, computer room
3) turn off the topbox motors
4) jumper out whatever motor was hanging
5) turn on the topbox motors
6) start guider program, which should come up this time
7) exit guider program
8) turn off the topbox motors
9) remove the jumper
10) turn on the topbox motors
11) start guider program
12) start real time system