Finding the Leak
What do a jeweler's screwdriver and cigarette paper have in common? Combined they form an effective tool for checking bassoon pads for leaks!
A pin vise like the one used to house small screwdriver heads like those used by jewelers doubles as a handle for holding the strip of paper.
This is called a pad feeler.
Slide the end of the strip under the edge of the pad. Be careful to place the strip so that it only contacts one edge of the tone hole and doesn't touch the tone hole on the other side.
Press or release the key needed to close the pad on the tone hole. Slide the paper out from under the pad and notice whether there's any friction or "grab" when doing this. If the paper just slides out with no friction, then you've got a leak.
Check the pad every 90 degrees or all four compass points (N, S, E, W).
There should be about the same amount of "grab" on all four points of the pad with just a little bit more "grab" on the point farthest away from the rod to which the pad cup is soldered.
If you notice a leak using this method, by telling the repair technician where to look, you may save time and money at the repair shop!