Hey Rally, don't believe everything you read!!! Just take the whole outside part out, trust me it will be fine. Whatever manual told you it was a bad thing was bullshittin', I've done it heaps of times.
You DO need to take the middle part out when you go to put it back in. The reason is, you need to "lock in" the tensioner mechanism when you tighten the outside part in, otherwise as you can imagine it begins pressing againt it and rubbing, etc. So while you have the outside out put it in a vice and undo the middle part Then "lock" the tnsioner into the loose position, put the outside part back in, put the hex-key in, undo the tensioner to the tight position, and put the middle bolt in and she's all done.
I'd use a new O-ring also when you put the outside part back in. Don't worry, they are worth about 30 cents from a seal shop!