I'd still be tempted to try and hold the pushrod while the engine is running, just to prove that there's no tight spots or if it grabs at any point.. With the above caveats of course. It might be that it only grabs and turns when the clutch lever is in and the pressure is on?
I've used an Oberon myself for many thousands of miles and so I would reccommend one, but if they came back with an unhelpful response from an enquiry about an issue like yours I would buy a FactoryRacing one.
Good luck..
