Ten years is long enough for the starter carbon brushes to have worn out. Try connecting a spare fully-charged 12v battery (could be off a car, doesn't have to be a bike item) across (or in place of) the bike's battery and see if that spins it up. If it does, then like John says the battery is dying. If not then the solenoid could be shot: identify the heavy cable coming in from the battery and the similar one going to the starter. Use a heavy spanner, pliers etc. to bridge across the terminals (you'll get a few sparks but don't panic, it's only 12V, it won't bite) - if the motor brushes are OK it'll spin up, suggesting the solenoid is kaput.
The other thing that could conceivably cause it is a very poor earth connection from battery to frame or frame to engine - if the starter doesn't get a good earth return to the battery it's the same as it getting a poor 12v feed. To check this, temporarily connect a thick length of wire between the battery negative and the starter casing while you press the go button :O)
Wedg1e, January 2008
