Take a look at the steering cable where it passes thru the hull and then connects to the "buckets".
On my boat, the cable has failed. I can look in and see the actual flex cable, and that should never happen.
Anyway, a turn that pulls the cable into the boat works fine whereas a turn that requires the cable to push outwards is less reliable. The interior flex-shaft can simply escape and bend instead of doing the pushing.
Your problem could be completely different, but it's worth a look.
