I love the LAMY 2000, but the one thing that's kind of confusing about it is checking the nib size. The hooded nib covers up the stamping of the nib size, so you have to disassemble the pen to check it. I've been asked how to do this, so I thought I'd break it out into a very focused video specifically on the topic.
The grip of the pen unscrews slightly above where the stainless steel stops, where the notches sit for the cap. Unscrew it all the way, and using your fingers only (no tools), try to push on the feed on the nib end of the grip to push the nib/feed unit out of the grip housing. It'll take a little finagling to make this happen the first time, but it should be easier after that.
Once it's removed, you can see the nib size and clean the pen more thoroughly. But, make sure you put it back in the right way, it has to be in the same orientation you pulled it out. Also, make sure you don't lose the ring that has the tabs on it, otherwise you won't be able to cap your pen!
This all sounds a lot more elaborate than it is, and once you do it a couple of times you'll be a pro. Just make sure you're careful and don't lose any parts or damage anything, there are no LAMY 2000 parts available through retailers, you'll have to go through LAMY USA to get new parts (and probably have to pay for them). And if you have a stainless steel L2k, the process is the same!