I have a ceramic top patio table with a metal base. The top is held to the frame via 2" plastic ring with 1 1/2 inch deep fine thread center. A plastic nut is screwed into place to hold the retainer center ring to the table frame. Over the winter the nut somehow came lose and is gone. I can not find a replacement nut and the table has not mfr ID on it. I looked into pvc replacements and no luck. Any suggestions. William