I needed to extend the bottom kitchen drawer to get to the hot water by-pass connections in winterizing my PC. After spending a long, unsuccessful effort I called Earl at PC and he gave me the simple method just like what Ron Dittmer had posted that I missed "the black plastic levers on the exposed side of the glides. When holding them up/down...it will come out with resistance. If it doesn't work, flip the up/down and try again".
Thank you Earl and Ron, I still have much to learn/remember..
Happy New Year, John