I think I need a new vacuum harness ... the one that connects to the damper door selector switch (part YH-1450). Anyone know the part number of a new vacuum harness, and/or where to buy?

And here's why I feel like it's the "fit" of the vacuum harness. I've tried a couple of new switches, but still get a leak when in the "off" position. However, if I take the harness loose and hold my thumb over the harness holes, then the vacuum pump will shut off. Pump also shuts off with selector in positions other than off, though Max AC doesn't work properly (diminished air flow and some through the defrost).

Ideas and solutions would be great! Thanks! (I'm running a 2001, 7.3, Ex)