Hi Daviesec,

Might be wrong mate but could be alignment, sounds too simple, try putting club along your toe line when you set up, to closed usually results in the putter wobbling away, because your trying to hold it in to your right side.

Great tip works for me every time, putt the club behind the ball and put your right hand on your right thigh, this squares your body great as long as the alignment is fine.

Hope this helps

Ian.