Originally posted by mgvh @hjb981: Thanks for the suggestions about cleaning the viewfinder. I checked, and clearly the dust is on the 'top' of the focusing screen. I.e., it's not on the side open to the mount. So, as you say, I'd have to remove the focusing screen. I guess I'll live w/ the dustiness for a while...
If you buy an after-market focusing screen, they usually come with a handy tool for r&r (remove & replace). Perhaps you could get such a tool if you plan on taking the screen out (I am not sure where to look without getting a screen though, which is obviously not justified just to get a simple little plastic pair of tweezers). Another tip is to put some lens paper over the mirror during r&r to avoid damaging it. Lastly, make sure that the battery is out of the camera, to avoid accidental activation of the mirror.
Anyways, I would also rather wait and just leave the dust where it was, until I was sure that I had covered all the hows and ifs on the r%r process. It is a bit fiddly, and there are obviously parts that you do not want to damage in there, and as you say, it won't hurt the pictures. Another option may be to have a service place do it. It should not be too expensive, because it is a pretty fast thing to do if you know how to do it (for me it took maybe half an hour, but I guess I could do it in 5 minutes if I practiced a little).