this type of bellows strap has long ago fallen out of favor
the permanent end is held firmly when new, it was not intended
to swivel, if it swivels it may also leak
the movable end is just a hole with a thin brass edge grommet
that you just loop over the pin sticking up to hold the bellows closed,
and if the strap is still flexible enough, you loop it back over itself and
also over the holding pin to keep it out of the way more or less
while playing. They do not snap onto those pins.
some pre-war Hohners used this type of bellows strap too
because you must stretch the strap a bit to get it over the pin,
then release it to hold, the strap needs to be both somewhat
stretchy and a perfect length, else it holds loosely and can flop
off easily. Once the strap dries out and loses it's stretch it
will break like this one has.
so ANY piece of leather the right thickness and softness can
be cut with a good scissors, and a simple grommet tool/hole punch
of appropriate size will finish the job.. it may take a few times to get
one the exact correct length and flex
therefore, outside of wishing to preserve authenticity, substituting
a more modern bellows strap and hardware is a much better solution,
especially if this accordion ends up in "playable" condition and
rotates into the Gig rotation, as the original bellows straps are unreliable.
this also allows for selecting something very nice looking and complementary
with rhinestone embedded snaps or your name embroidered onto the
new strap. There are also grommet type snap setting kits at the hobby shop
and leather supply shop.
if you wish to try making a pair, Tack shops usually have some fresh, nice, basic
leather lariats/leads in that width and thickness in brown and black ready to purchase
buying an old used pair from eBay they will be dried out and not take
the stretch needed when looping over the pin and quickly fail
ps: love the sharps and flats ! quite unique