About this 3D model

A button I'm working on for an iPad Pinball table. It uses a part from http://www.thingiverse.com/thing:2526. It is failing manifold tests. I ran it through Meshlab but when I re-import it to blender it fails manifold still. I tried to print it anyway but the geared rack part doesn't print well yet. Any help would be appreciated. I'm a blender noob. It will not print correctly without support structures.