Yes, it is usually the pad that is worn and will not allow the shaft to stop. Test it by selecting 'neutral' on the lever and using a piece of 2x2 wood or similar and jamming it against the shaft. The shaft should stop now.
It is only oil drag that is turning it but it is strong enough to turn a light implemet.
Replacement is straightforward but complicated a little by whatever (if any) auxilliary hyd arrangement you have. Drain the oil and remove the left hand round cover. You will see the independant PTO unit with the pad and cylinder on top. Remove the housing 23, complete with the pad. There is a very small O ring between the two so make sure that you don't lose it. New pads have a rough facing for better operation. Check the piston for wear. If all is OK reassemble but don't overtighten the shouldered bolt.
DavidP, South Wales