I just ended up using brute force. Maybe mines a bit off. Has no plastic insert either and it seemed like it could come off so I've put a dab of CA on it to secure it. Broken in the motor (that prop is scary!), aligned everything so that it should hopefully fly nicely. Just have to wait for the weekend now.

UPS man just dropped off the big Cessna so I will have a bit of fun building that and as it has a steerable nose gear I can practise taxi-ing around the house unlike with the cub.