If you pull the trigger with the safety on, the hammer drops a very tiny bit, then when the safety is turned off the hammer will fall and fire the chambered round. Not a very safe thing to have happen to your race gun.IIRC, the Springer P9 was actually made by Tanfolgio, so I'd imagine you could use the Tanfolgio/EAA Witness part to replace what you need.
What's wrong with the gun?