185 stab trim/CG question

I know we're talking about a leter model 185, but FWIW that clicker feature started in the 1958 model.
So the earlier 180's (unfortunately) don't have it.

Finally got a chance to look at the elevator down spring setup. The book says that with the stab LE full down it should put no load on the elevator till it passes through 0deg streamline position. On my plane with the stab LE full down the spring is under light tension. Could this have an effect on the still stab I am seeing at the higher speeds?
Can someone explain the function of the elevator down spring?

Tom