On Mon, 24 Jul 2006 23:38:57 +0100, "Dave Plowman (News)"
wrote:

It's worth buying a cheap [stethoscope] from a medical shop.

Don't waste your time with a medical stethoscope - the design of the
bells is different, so as to make them useful for listening to
widespread sounds from squishy things. If you're after mechanical noise,
get a mechanic's stethoscope with a rigid probe connected to a diaphram.