04 XC70 vacuum brake booster switch

[kevabar]

I am having some brake issues. I rebuilt all calipers with rebuild kits. I took my time and cleaned them up nice before assmbly. New rear pads- front are still good. The caliper springs are installed correctly. I flushed out nasty fluid with Pentosin Super DOT 4. I went back twice and bled all four corners starting with LF, RF, LR and RR. And the brakes are still mushy.

Then we noticed this funky little valve with a spring hanging out up near the air filter. I put 2 zip-ties in a criss-cross fashion to seal all back up. Turns out this is the Vaccum Booster switch. It seems to brake frequently. Will my zip ties work or does it really need replacing? (Brakes are still mushy with my MacGyver.)