Rheich Axles?

Has anyone ever fitted replacement roller axles to thier caravan, I have a Rheich mover the old grit type rollers are just about worn out, I bought some replacement rollers the new type none grit.

I understand from Rheich they are simple to fit got the instructions but can't get under the caravan, do you jack up the caravan and remove the wheels ? any help please.

Mal
May 2012