Can you replace 1 weft thread that picked up some wrong warp ends on a plain weave finished project?
Yes, you can. It is very difficult to do this after the cloth has been washed but not too bad if you do it straight off the loom. Sometimes I do it on loom if I notice it because the tension helps. You just need to put a replacement piece of weft on a needle and weave it in correctly. There should be a good overlap for 1 1/2 inches on either side. After it is needle repaired you can snip out the offending weft and you hopefully won’t see anything after it is washed.