Smooth helix spring - 1/2 revolution beginning and end

Hi,

I'm trying to create a spring with a regular 1/2 rev turn with no pitch at the beginning and end.

I created it in a different feature after creating the spring, using a swept boss.

Thing is I get these lines showing where the spring ended and started and where the feature to complete it with half a turn begins. How do I "smooth" these elements?

Thanks

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