First make sure the top nut is all the way down ,not tight just a little loose. take off the the lever , remove the bearing cover ,that is the one on the outside,not the one on the lever side. Now tap out the gear being careful not to damage the threads on the pin. Next just undo the top nut and it should wind out until the spring is loose. Regrease and put everything back the way you took it off.
If the spring is original should come a part easily ,if it has been modified you might have to compress the spring.