I did all that stuff too, worked for a little while, then, zippo!!
Here is how I did a longer lasting fix (lasted a few weeks anyway!!)
You know that little metal ring that makes the contact with the posts?
Well, remove it, and using a very fine grit sandpapper, polish the "contact" side and put it back on. If you can get some contact enhancer, you can brush a little on all the contacts and that works great (again, for a while!!).
Doing all that, (oh, and rotating the posts) made mine work for a few weeks. If you press the button down and get no contact, simply rotate the little black button about a 1/4 turn, then it shoud make contact again.
Of course, I want a PERMENENT fix!!