Audio Technica AT 666 is loosing air

The guilty part is the air intake valve. It holds the vacuum for about 30 seconds and then releases allowing air the get in.
Is the inside valve/diaphragm easy to fix, want to know before I start taking it apart.
Thanks again

Hi. Same issue with loosing air. Did you solve it?

Dmkbox
No did not, decided to put it away to solve another day.
It's been in my heated attic for a bit as the last post was 08.
Time flies.

Hi Rugyboogie, I also have an AT 666 that won't hold vacuum. Some time ago Raul suggested a new securement line around the perimeter but I have too many other projects ahead of this one.

If your test identified the air intake valve, can that be disassembled and repaired or replaced with help from a tire or bicycle shop?

Yes, guilty part is little rubber valve-in. I found no solution to replace it. There are special form rubber T insert. It's looks good, but not hold vacuum.
Only solution to close valve with rubber cup. Or DIY valve.
My skill not so high.