when I took this apart i needed to use a lot of heat on the collar to free it up from the spindle I also used a stilson with a pipe as leverage to spin the collar whilst wedging the inner spindle so that it couldnt move. I used a mix of oil and petrol as an anti sieze the petrol carries the oil into the mechanism by capilary action and then evaporates away (dont apply the heat until the petrol has dispersed) When heating be careful with the flame as its easy to scorch the wood.
Dom