When I tried to fix my wiper delay unit I found it hard to get the right size rubber/foam behind the clip to control the valve, so that pushing the rod would blow air out, but seal when the spring tried to push the rod out. Just got a genuine NOS unit, and it leaked as delivered. On removing the metal clip, the black foam in there disintegrated. I cut a new piece of foam, BUT i also smeared the inner face of the valve disc with vaseline - now it holds vacuum fine. With the bleed nipple blocked there was some resistance to pushing the rod, so I thinned the foam a bit. The new unit came with a different orientation on the bracket, so I had to rotate it some - holes already available. To make it easier to install I cut slots from the mounting holes to the end, so I could have the screws started, and slide the bracket in - all back now. The reason my origoinal had its bleed nipple broken off appears to be the original black tube is as hard as, so I fitted a few inches of thick wall rubber vacuum tubing as a bridge to the nipple. Should all work now, as long as the tube to the adjuster is OK, and the adjuster doesnt leak. Tests for another day.