"The observatory attaches to the Ariane 5 rocket via a launch vehicle adapter ring which could be used by a future spacecraft to grapple the observatory to attempt to fix gross deployment problems. However, the telescope itself is not serviceable, and astronauts would not be able to perform tasks such as swapping instruments, as with the Hubble Telescope."
What I don't get is why we aren't at the point now where these deep space objects can be set up in advance for robotic servicing. For Hubble we could send people to work on it. For JWST we can't. But either way, wouldn't it be possible to set up some very precise mount points and fiducial marks so it might be feasible to send a robotic service mission that can literally remove panels, non-working parts and boards, and replace them, maybe without any human intervention? I know that is "high tech" even for where we are now, but it seems to me that we are pretty close to being able to do exactly this. Putting the mount points and fiducial marks on the deep-space satellite now even if it takes 10 years before we can use them would be a good idea.