OK. I forgot to mention that it's a good idea to soak the brass collar bearing cover with WD40 the day before to help it slide up when you hit the swan neck.

hi got same problem should the small bolt stop the collar moving and then allow the swan neck to move inside

No, according to Dot Piper, you don't need to touch the small bolt. I can't remember what it's for but it doesn't stop the rudder post moving.