With light tapping using a hammer, the metal is pliable enough to reposition. With every tap you need to be conscious of the possibility of deforming the exterior surface. Having someone hold a piece of soft wood against the outside is necessary.

When prising the seam open care is needed to open no further than necessary and to keep the open seam as uniform as possible. The metal edge I used for opening was sharpened on a grinder to help it push into the seam.

With these projects I generally have the help of a most capable neighbour.

Take care,
John H from Downunder