Glad I tried the tire deflator on the driveway before trusting it in the desert. On the first tire I blew out, the small U-shaped piece of metal on the nozzle that prevents the control valve from being removed came loose. This allowed the control valve to be completely separated. Luckily I noticed the little U piece and was able to reattach it. two pairs of hoops and make sure it goes deep into the groove (maybe it wasn't fully attached and slipped when I moved the spool up). It is now securely anchored deep in the groove and hopefully this is a permanent fix. It's working fine since I've been using it now, but I'll continue to monitor the integrity of this small part. When it works, it works quickly and efficiently. If it doesn't drain very quickly, you probably haven't removed the valve core.