Something sticky is in the threads... Try very hot water in the sink as a start, while boiling some water on your stove. With the glass and plastic preheated, install them to the blender base which must be unplugged for the rest of this adventure. Pour the boiling water in, only to about 1/3 of capacity. Install the top cover to protect from the hot water. Hold the glass by the handle and with a rubber glove on the opposite corner or pour spout side. Hold high to avoid the heat from the water. Have a large burly man hold the blender base so that you may twist the glass container counter-clockwise. Stop as soon as it starts to turn the plastic ring off...and go the the sink... Continue after pouring out the hot water. Remember that his procedure is likely to cause broken glass or broken plastic and exposure to scalding hot water. If those risks are acceptable you should still take precautions to protect your flesh. Otherwise order a replacement ring and pitcher for the blender.