What is a good way to clean the yoke on N AT1? I used a can of contact cleaner but rsn out before it was as clean as I like. Also is it necessary to polarize the dynamo after removing the yoke, it made a big spark when I did it the first time. Was not expecting that. Trying to change the crank seal but did not have the correct puller so will have to try again when I get a long enough bolt.

This is the style of puller for the generator AT1 & steps right down to the end of the hole. My AT1 is magneto flywheel ignition so different puller for mine.