I have a good down jacket since 7 years ago. The last time I got it cleaned in a specialized shop I found that it lost half of the down filling, but unfortunately I didn't check it at that moment.
It's specially in bad condition at the shoulder and higher back areas because I used it with a backpack.
I would like to repair it myself by adding new down.
Is it advisable to perform small cuts in the inner side (of every affected section), fill it, and sew it?
Or this (sewing with a home machine) would tear the fabric?, Is it better to try to unsew existing sewings?
Where can I buy 850+ down filling?
I've found some at Amazon but they sell 3 pounds of bad quality down for $90+shipping but I only need less than 1 pound, maybe 1/2 pound is enough. I couldn't find it at eBay.