[7s26b]

Try an SR43W - as some of the other battery types are now universal and may not fit properly.

 

[7s26b]

According to the latest Seiko list - it's an SR43W.
Battery manufacturers have, over the years reduced the number of batteries they make and have made a few sizes multi -fitment - with the result of batteries not fitting correctly.
Therefore a modern 386 may not have the correct dimensions, this is a known problem, and has been discussed on the forum before.