Air leak from TPS on Newage STi.
 

Hi guys, have searched but can't seem to find much of an issue, has some boost issues so been pressure testing all my pipe work and in doing so I have found a large air leak coming from the throttle position sensor.
When I remove the TPS the air leak appears to be coming from the throttle spindle, there is a seal in place but doesn't appear to be anything holding it in place.
Anybody know if this is common and any known cures?

Cheers Ian.