Same problem here...
I had the exact same problem with my Sioux – it is one very important o-ring, not too difficult to replace – Here is an excerpt from my build log where I documented what I did. I used a #83 size o-ring – I picked it up at the Lowe’s Aviation and garden supply…or was it Home Depot aviation and garden supply? If you need clarification, let me know.
...from my kitlog - 1/14/2016...
http://www.mykitlog.com/users/displ...ear&project=2191&category=0&log=221135&row=14
I have had a bit of an ongoing issue with my beloved Sioux drill. It works flawlessly for long periods of time (4-6 months) and then it doesn't work. It's like the air pressure doesn't get to where it needs to be to spin the drill...just nothing. Unless you unplug the air hose, pull the trigger, and then reinsert the air hose - then it would work - at full speed - untill you released the trigger, then nothing again.
Bob fixed the inoperable drill one time when he was in town by flipping the o-ring over and reinstalling it. I tried that too but that little o-ring is really hard to get to at the bottom of the narrow handle shaft and I couldn't seem to get to it - luckily, when I put it back together - it magically started working again.
I also took it to Avery once to have him look at it when it stopped working and he was stumped too. After fiddling with the thing for a few minutes and switching out the spring, the impellor and some other parts from a working sioux drill that he had - my drill still wouldn't work. Then all of the sudden, it was working...so I left it alone again until today it stopped working again.
There is an o-ring in the handle assembly that a valve sits on, this valve looks like a small impellor and it has a shaft that runs up the middle if the impellor and contacts the trigger. As you pull the trigger, the shaft causes the valve to lean slightly and open up the air flow which spins the drill. big pull = large opening, fast drill speed whereas a small/slight pull = small opening in the valve and the drill goes very slowly.
The one common denominator seemed the be that o-ring in the handle assembly. I had even purchased a box of replacement o-rings - but I just couldn't seem to get that little sucker out of there as it sits down in a channel and it's very hard to get the pry tool in there and get a grip on the rubber o-ring and lift it out. I even asked Bob what the trick was and he said that he just used my pry tools and got it out...
So when the drill quit today, I was determined to fix it. I worked and worked and finally got that o-ring out of there with the 45 degree pry tool. Now for the also-hard part of putting that o-ring down in the bottom of the handle, and stretching it down into the channel. I could get it to seat on one side, but then the other side would pop in, popping the first side out. There isn't room to put a bunch of tools down in there (it's narrow, remember) so I devised a way to keep the o-ring seated in the channel by using a long, thin piece of stainless steel that I cut from my remaining sheet.
With the stainless steel tab, I was able to hold the one side of the o-ring in the channel and then with a flat head screwdriver, I could stretch and seat the other side - and the o-ring popped right in place! I put the drill back together and it works great again! This is my notes for when I have to fix that drill again...
