Hi Neil,
I reworked the areas shown in the photo.
I moved your arm cut over slightly as the thickness from front to back was to thin for a 0.25 fillet top and 0.625 fillet back.
Also the neck cut out curve had a sharp corner where it should have blended and gave a strange result when Boolean difference was applied.
This was the order I filleted.
1) Fillet back 0.625 but not the top edge.
2) Fillet top 0.25 again not top edge.
3) Boolean difference neck cut out.
4) Fillet top edge 0.2
Attached is the result.
Hope this helps
Barry