what kid of dust cap on the crank? OH just where do you live the beach somewhere? I would use alot of that PB blaster stuff and then drill two small holes in it like for a shimano crankset, assuming you or your shop has the shimano tool. I thought that hole was either a vent hole (most likely) or maybe a chainholder but it seemed low for that.
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk