I’m a relative newbie, and have been slowly but happily making progress on my practice set. Had to put the pipes aside for a few weeks, and when I tried to resume playing, the bottom hand had “disappeared”. Can play the top hand (somewhat weakly), but the bottom hand only gives me the second octave. As a new guy, am nervous about messing with the reed or the staple. Anyone have any suggestions as to what might be wrong or how to correct? Thanks for your help. 
NJ eh? Sounds like classic dry air syndrome. If the air in your home causes the reed to become dryer than it is accustomed to being, it will weaken the reed and cause problems similar to what you have described. I would not adjust the reed for now but instead would try leaving the chanter for a day or two in a more humid environment and see what happens. If it is just lack of humidity, it will probably come back to life on its own.
the reeds probably ok sounds like one off your middle fingers on you r bottom hand might be missing the hole a tiny bit.or sometimes your fingers on your right hand just change shape.it happens when you play alot. so tape the bottom four holes with tape and just use you top three and blow gentley and if you get a d your ok. and you will know then.
gotta agree with wydeboar. Try making your pipes-storage and practice areas more humid with a case humidifier ($4 at a guitar shop) and/or a sunbeam-type acoustic humidifier (~$35-$40 at a pharmacy).
i am in new j as well and my pipes are fine, except for the regs where abouts in jersey are you?
I’m in central jersey, about two miles south of the bay. Due to asthma etc we have to have the aircleaner and humidifier running almost constantly. the windows are never open, and there’s never a time when the heat or air conditioning (the only times the air cleaner runs) isn’t on. The temp and humidity in the house remains constant, winter or summer, rain or shine…
We bust my mother for “hermetically sealing the house.” Can’t say it’s an appealing option to many, but it’s one way to go…ah the sacrifices for pipes 
Here are a couple of tests you can do, after trying to get the general humidity up in your house etc:
Blow into the bag a few times, let it get good and humid with a few deep breaths. Then play a bit. Do that a few times and see if the reed opens up. What happens when a reed dries is two-fold, one the cane itself loses the arch, so the elevation or gap in the lips closes. The cane also shrinks a bit, so the bridle or belt actually loosens, and can even slip or vibrate down, sometimes at a session or gig, with embarassing results during a tune. So, if you don’t get big results with a little (I mean a little) humidity then very gently move the belt up toward the lips a fraction and look at the lips, to see them part just ever so slightly more. Then try again and see if that heals the playing problems.
You can also blow directly into the cap of the chanter, but don’t tell anyone I told you to do this. I’d puff once and try. More than a puff or two will either work or not so you’ll only damage the reed and wet down the cap inside by blowing and blowing into it. If the reed instantly firms up flattens down and fills out particularly in the lowerhand, then you know it’s moisture related, but the only fix you may have for that is resetting the belt for the winter anyway.
Royce
My chanter has a C key and when I start losing the bottom hand (bottom D autocran, E and F jumping octave or squealing) I know I need to add a little olive oil to the leather pad on that key. I don’t play this key yet so it usually has a rubberband on it to keep it from leaking. The problems are pretty similar to when reeds made in wetter places start to dry out and leak down the sides. What I notice is that my chanter becomes completely intolerant of any tiny leaks around my fingers.
Good Luck
Ehr..
“A dirty mind is a joy forever” 
Amsterdam. Fitting.
But I feel like I need a shower.
Royce