Sounds like there are several possibilities for what the actual
problem might be. I guess I'll call a professional - I just know it
it'll hurt having to fork over a lot of $$ for what will likely turn
out to be 15 minutes on site. I'll just have to comfort myself with
the fact that it will probably be half the cost of having to call them
after I botch the job myself. :-)

Thanks for all the replies.

-JJ