The replacement of the o-ring is not a huge concern for me, although I like to see what I am getting into before I start a repair as a general practice. The system is self purging so that is not a factor. GeorgeI can't see why you would need a manual to repair these, they should be straight forward to remove and replace the seals. All rams are basically the same, just make sure the seals go the correct way around and use lots of oil, you can't go wrong.
The only concern is purging the air from the system, it should automatically purge but i cam not 100% sure on this.