I have recently received some Clearpath CPM-SDSK-3421S-ELN servos and realized that the motor shaft is not keyed like the steppers that Avid sells. Instead of a key sticking out of the shaft, the Clearpaths have a notch machined into the shaft. I assume the notch is intended for couplers with set screws (although Clearpath advises against these in their manual)? Is it ok to use the keyed Oldham couplers that the Avid machine ships with despite the shafts not being keyed?