Hi Again
I checked on line and sure enough they are exactly the same as when I was an engineer 20+ years ago.
So Mole grips on spindle (not on the part the belt rons on) use a rag or glove and hold the fan to stop it turning....turn the spindle CLOCKWISE as if you are doing it up.
You may have trouble holding the fan still.....look for the hole in the armature to help.
Good Luck
(They were called Cimex C40 when I did them) and I considered them to be rubbish......Sorry!
Steve
March 2008