Missing Steps on Motor

Hi All...

Having a slight prbolem with API CMD-260 driver, its going a bit to
far in one direction of travel. I've tried the 1K resistor trick
listed on ktmarketing (Tim's) sight where I got these things from,
but when I put the resistor in the drive stops completely until I
take it out again. Some starting basics:

- running TurboCNC
- OPTO is 5.16V
- Line Low is .605V
- Line high is 4.90V
- Microstepping at 2000

Any ideas greatly appreciated!!!

Brian