created the pattern too big

Hello there. I have a problem at the moment. I have designed a pattern which I want to turn into a brush. However, I initially created the pattern too big so I have been trying to reduce the size of the shapes in the pattern to make the brush smaller.

When I try this, the elements in the pattern do not downscale properly and bits end up sticking out where they shouldn't and shadows do not stay in line.

I don't have snap to grid or point activated and do have scale stroke and effects ticked.

Can anyone please give me some advice?