Finally got out this weekend to test run my "winter production" of crank baits. Most required little or no tuning except one. Of course, this is the one I really liked due to a paint job. How I can make the same model several times and have one not perform still baffles me.
Skeeter, of course, is correct. I asked him the same questions you are about two years ago. Number one issue is weight. Low in the belly works best for me. Second is the "line of sight". Look down the bait and make sure the line is correct. Belly and back, hooks, and lip/tie is all in line with each other. If it blows or loops in the same direction, look for the imperfection that would allow this to happen. It is the little things. I have had a lip in straight, but it was deeper on one corner than the other. This allowed it to dig at one corner and caused it to loop as you have suggested.
Hope some of this has helped. When you find the issue, make sure you add in a process to correct it when you build the bait. Document everything. This saves on the frustration index.
Spinner.