Most driver boards have some extra unused transistor drive circuits. If
you're in a tough spot (on a service call, just before a big party, etc.)
when you do not have a necessary transistor for replacement, you can 'steal'
one of these unused transistors and move it to where it's needed. To do
this you'll need to check the schematics and identify an unused component,
and then carefully desolder it using a non-destructive desoldering tool such
as desoldering braid. You must be careful when doing this so that you don't
overheat the board which may damage the component(s) and cause lifting of