I wouldn't be panicking. The upper bearing and collar is very easy to replace, maybe 45 minutes.
When the ball bearings fall out, everything falls down slightly and it destroys your horn ring with the plastic tab that cancels your turn signals. New horn ring is also very cheap.
Hardest part was pulling the shaft back up into place while reassembling. I just cut the old collar nearly in half and used it as a puller.
Read through this thread:
http://forums.pelicanparts.com/porsche-928-technical-forum/834267-steering-wheel-bearing-issue-help-please.html#post8309987