are you powering the BOB and motion controller from the PC's USB ports ?
did the breakout boards inputs fail or the outputs to the stepper drivers ?
how long did the C10 and Chinese BOB's work for
Do you still have the C10 ?
the old version has sockets making it easy to replace the C10's IC's
both BOB's have a direct connection between the switches and the 5V logic IC
a stray connection applying more than 5V to the BOB's input will damage it
what kind of limit switches do you have ?
1) mechanical micro switches
or
2) electronic proximity switches - if so what is the supply voltage to the proximity switch
the Chinese BOB has a design error
(see the top left hand corner of the circuit diagram)
the 74HC14 IC that connects the inputs to the 25 pin printer port connector
has no 5V power to the supply pin 14 !!!!
this can result in incorrect logic levels to the PC printer port or motion controller
I reverse engineered the BOB to see why the BOB did not work as expected
John