Steering shaft/u joint
 

Got steering shaft replaced and symptoms got better but havent gotten away, steering is still notchy and has a small vibration.. im going through a friend of a friend who has their own garage and ten year mechanical experience but this is also my first time getting work done there . Could it be a defective part, a lack of grease, or just a lack of experience on the mechanics part? Problem was pre-diagnosed by the previous owner of 7 years mechanic so its not that it was an unnecessary part. I also got the part verified before purchasing and visibally i can see that the defective part was replaced. Any ideas?