I know Mazda had a recall on the top, where it would get worn out where the frame contacted the top itself. I would contact your local Mazda dealer and have your vin# handy. Its worth a try since top replacemant isnt cheap.
If I remember correctly it had something to do with rivits it the top frame rubbing on the cloth top.
You can also search over at miata.net for more answers and fixes.
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