Erratum 1 for the LTC4015 says that the top mark date code 1716 and higher doesn't have this problem. I cannot see this top mark. In our older series (which has the error) the top mark was 644 - 4015 - B47862.
The new series is marked 744 - 4015 - B31705. Is this sort of the new date code?
Kind Regards,
Patrick.