Is it fairly easy to do?

Yes. Watch a you-tube video and you will see how easy it is. You need some internal circlip pliers and do not scratch the shaft

read this

The only fiddly bit is the circlip removal and refitting. My tip is to use a socket to push down the air shaft rod and plastic fitting thing enough to remove the circlip. It also serves to protect the shaft at the same time.

Dead easy – just don’t use too much grease reassembling it or you’ll block the +ve/-ve transfer port and you’ll lose travel.