Hi -
How can I sew a button back onto my couch? The couch back is slightly tufted.
Is there a special needle that passes through the couch from back to front?

Syringe Tufting Needle, Button Replacement Needles, Nails, Needles, and Pins, Button Replacement Points, Syringe Tufting Needle from Rochford Supply - Your Online Textile and Upholstery Superstore!

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The first link is to a button replacement tool or button replacement syringe
The second link near the middle of the page shows you how to properly use this tool. This way you don't have to remove the back of the sofa to get the job done.