Light or current, is there another coral close by on the side that the coral is leaning away from?.. or is there a current cross another coral from the direction the coral is leaning from?...
The direct lenear flow is probably the problem. position you pump so that the water just passes the coral causing chaotic water movement all around. do not blast him directly. you will need to experiment to see just where the coral likes the flow. when it is happy it will stand up and should bud out.