It is best to try to isolate the problem.
First, loosen the grub screw that attaches the flexible shaft coupler to the OTA's focuser. After doing this, the OTA's focuser knob should be free to turn and control the drawtube length.
Then, connect a computer directly to the EAF (do not share the bus with any other devices). Connect a 12V supply directly to the EAF, if it is the original 12V version.
Run one of the programs in ASIStudio (ASICAP should be sufficient for this). In the ASICAP's focuser window, you should find an Advanced button - click on that to get to the hidden parameters. Be sure to type Enter after you change a text field.
If the EAF is a 5V model, make sure the computer's USB port is capable of supporting 100mA. One of my EAF draws 80mA when it is not moving (and probably more when it is).
See if the EAF behaves correctly when isolated. If it does, the problem is elsewhere. If it still fails, then you could have an EAF that has given up the ghost.
Chen