KEB COMBIVERT F5 Reference Manual page 308

Diagnostics and Troubleshooting
Problem:
Unable to complete Encoder Pole
Position Learn successfully
308
Troubleshoot:
Ensure brake picks and the sheave is free to move relatively
easily; should be able to rotate by hand.
If the displayed position does not appear to change and the
sheave does not move back and forth by a few inches, then
the sheave is unable to move freely and the procedure cannot
be complete.
Ensure correct motor U, V, W phasing.