If the needle is good, the presser foot is good and the fabric pivots as you sew, the most likey cause is a misalignment of the presser foot and feed dogs.
To fix this I use a pair of metal 6" rulers. I place one along the feed dogs then lower the foot and place the other along side the foot. You can easily see if there is a misalignment by doing that. Then adjust the shaft at the locking screw so the foot and dogs are in alignment.
Also relieve the presser foot tension before you do that and make sure the foot is down far enough to rest on the needle plate when the presser foot is all the way down.
Joe