If you read past the first post on the thread you referenced, you are describing the same fault he had.
His original post was just quoting the possible causes for the fault. The fault was actually telling him his spindle enable signal [M1SPDL_ENBL] is on but [M1SPDL_READY] is off.
This is saying the control is outputting the spindle enable signal, and it expects to see a spindle ready signal back from the drive within a specified amount of time. If it is not seeing this, either the spindle drive is not ready (i.e. faulted), or the drive is outputting the signal, but it is not making it to the control (i.e. bad connection, broken wire, bad relay, etc).
I'd start by checking the spindle drive for a fault, and if no fault on the drive, check the wiring between the drive and the input to see where it is being lost. Look in your electrical schematics to find the wire numbers and terminals to check. I don't have prints with me, but I think there is also a relay in this circuit you may need to check.