Sorry, I feel your pain. Try and remain optimistic, don't assume the worst until you KNOW.
Optimism won't fix the problem, but it won't ruin your day. Do the diagnosis, and even if things still point south, do a tear down to confirm.
I speak from experience... Just because you assume somthhing is toast, it's no reason to liven up the mood by going at it with a sledgehammer; sure, it's fun, but when you find it's just a bad gasket, that's when you find out how bad a day you really can have.
