lines of rare particle hair

I’m rendering a chair and I have hair particles on it. It has 7 500 000 particles and when I render it you can see there is a line, actually two lines of rare hair (you can see a white diffuse material behind hair). It is like the hair isn’t distributed evenly even though Even Distribution is checked. See the pictures below.

In the particle system try checking the checkbox for ‘Use modifier stack’ If you already combed the hairs, you will need to click ‘Free edit first’, then check it, and then re-comb it. If you combed the hair, save a new version first in case in doesn’t work you won’t have to recomb it.

Subsurf should be the same for viewport and render, and the particle sustem should be below it in the modifer stack.

I can’t find the free edit first button…

It’s here

Ok, thanks.