During each startup the rotor accelerates a little bit above turning gear speed of 6 rpm. The turning gear will then become uncoupled from the rotor. It is only after the rotor speed reaches 0 rpm will the turning gear rengage. The process then repeats itself. In 2006 the turning gear was damaged and required an overhaul but since then, the problem persists. Has anyone seen this issue? What could be driving this?