Ron, persuade? You must be joking. If you were an abo it was your course commander, CNI and poster that determined your posting.
If you were a retread there was indeed some persuasion or more like mis-selling. We had an ex-Canberra nav and an ex-JARIC nav and both had been given the fast ball albeit for the 4 month course. Another retread decided he didn't want to pass and did little work in ground school. At the culmination we underwent a Viva with all the kit set out but power off.
His Viva lasted 7 1/2 hours. Needless to say, they wouldn't let him fail.