Pack repair, ChCh

Trying to find someone willing to attempt to sew up part of the harness on my older macpac cascade 90. Last time I wore it something hard in the lumbar pad area started rubbing through my skin. I did the rest of the trip with an inner sole stuffed into the back of my pants. Macpac sent it away to their "repairer" but they couldn't do anything with it since they use a different harness on their current cascade. So I carefully cut open a flap to reveal the lumbar pad, a piece of stiff closed cell foam with a layer of soft open cell foam glued over it. The soft layer had either compressed or worn away at one corner, allowing the edge of the harder layer to press through. I've glued a new layer of soft foam to the hard layer so now the flap needs to be sewed up or patched over. Don't care how it looks but I don't think I could do it well enough to last very long. Any recommendations?