Shame you are not in the UK Dave this is the answer I got from my email to Hegner where I have an account:
Dear Frank,
Thank you for your email, I’m very sorry for the delay in getting back to you.
I have spoken to our in house engineer and he is not too sure how this could have happened either. He’s quite curious to get his hands on the saw to have a look.
Could you please forward the customers information on to me as we will look into getting this saw collected for inspection and repair or replacement (dependant on the outcome of that inspection).
I look forward to hearing from you shortly.
Kind Regards Chris Wilson Technical Support Advisor
Does not help with why but an engineer would of took a good look at it and if no fix found straight replacement may be worth contacting your supplier and bringing it up they should do the same. On the other side of the coin if the main Hegner engineers have not seen this issue before and want to look at it to see why it could be an issue with the clamp position blade position etc and not a fault with the saw may be a good thing if you get what I am saying, I would definateley throw an email to your supplier I would even tell them Hegner main office do not know what it is and recommend an engineer look at it they will probably just swap for a new one I am guessing and send back to who they get them from for a look at. Good luck sorting it out .