It is a bit like pot luck.
As people have said before, some will need grinding off. I have had to do this a couple of times.
The method that I use is to pour a little thin oil down the drive tube, then after a couple of days get it as hot as you dare and bash a 5/16" rod down the centre of the square section tube whilst holding the drive tube.
Generally they will start to move after a couple of hard bashes with a lump hammer.
The ENFRL that I picked up last weekend fell apart, and still had grease on the pinion drive, no sign of rust at all. I love "salt free" seagulls much better for your health

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H-A