RE: Nock it off!
The best way is to have the center serving replaced with one of smaller diameter. If you don't have the knowledge or the tools then it should be done at your local shop. Usually doesn't cost but about $5 and will cure your problem. Serving material typically comes in sizes like.018", .021" and .025". Couple thousandths doesn't sound like much, but when doubles around the string a difference of .003" actually becomes almost .012", quite a difference.
You also can try different nocks. Some have a slightly larger throat than others. If you are using uni-nocks you could give the 3D version a try.
My advice? Get the serving job done.