If you are going to replace the cable, you must wind both ends of the cable around the spool to take up the slack before reassembly. I know it's a fiddly job.
I didn't and assumed that operating the motor would take up the slack. It did not work; it distorted and frayed the cable. I have just ordered a new one. At least it's only £15.99 on ebay. You will pay £150 plus for a new regulator.