Quoted from ryanwanger:
Read through that other thread. What exactly is the benefit? Faster response from the switches? Anything else?
I think what happens is with the series resistors in place you can get situations where say a set of drop targets are all closed in one strobe which pulls down the voltage. Then the return may not be seen reliably.
The black knight manual has a little blurb in it about the resistors (after BK at some point all the resistors in strobes and returns went to zero ohm). Info is probably on pinwiki too. Basically change the series resistors in the switch drives and returns to zero ohm. Top right corner of driver board near the switch plugs.