To get to the oil pump, you have to remove the gearbox and clutch assembly.
Odds are, it is fine. Most folks, if they are in there for a rear main seal r/r, will replace the o-ring on the oil pump cover.
At some point, if you keep this bike long enough, you
will learn to do all of this. Do you have the original tool kit and owner's manual? BMW gives you a very good head start on ownership with these two items. MUCH better than the competition.
edit: AH! Clapet! I had to Google it.
Yes, there is a spring-loaded bypass valve in the oil filter compartment. I have heard of the spring breaking, and the spring pieces can get into the works and really mess up your day.
Here is some discussion about it on Boxerworks forum:
http://forum.boxerworks.com/viewtopic.php?f=1&t=1046&p=12703&hilit=ball#p12703and
http://forum.boxerworks.com/viewtopic.php?f=1&t=217&hilit=oil+pressure+springedit 2: if you have signs of oil weeping around the filter cover, DO NOT tighten the fasteners tighter! You could easily strip the threads in the engine casting!
If you do have weeping, you might need to read this article about how not all oil filter canisters are installed to the same depth.
http://www.gunsmoke.com/motorcycling/r100rt/oilFilterCanister/index.htmlThe idea is to measure things, and amongst the paper gasket, metal washer and rubber o-ring, you can adjust to get just the right "crush" on the o-ring to make things tight.
In my case, all I had to do was quit using the paper gasket, and all was wonderful with the world, or at least, that small part of one motorcycle engine...