I assume you have cylinder steering.
Turning the wheel pushes fluid down one pipe, which pushes the piston in the cylinder to one side. Fluid from the other side of the piston pushed back to the helm unit via the other pipe. The thing to remember is that the piston will be on the opposite side to the engine. i.e. turning left will move the piston on the right.
How did you bleed the system?
Did you just open the nipples and pump fluid through with the engine in the middle or to one side only? If you did you are sure to have air in the cylinder.
From memory you should.
1) Turn engine full lock to one side (say left). If the system is dry, you will have to move engine by hand.
2) Secure the engine there. (Tie it to something)
3) Open nipple on the opposite (right) side and "steer" right until there is no air in the expelled fluid.
4) Close nipple.
5) Apply full lock to other side. The engine should turn by using the wheel. If it won't, you still have air in that half of the system.
6) Secure engine.
7) Open left nipple and "steer" left until no air.
8) Close nipple.
Also make sure that the helm pump has a good supply of fluid so it never drops below full.
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