I've got a Oster, not quite like that, but most blenders I have used run into the same problem:
The blending area is very small compared to the actual width of the blender jar. Or to explain, look at the bottom of the Vitamix blender jar, see how it is almost as wide as the mouth? Food never really gets funneled and compressed and thus stuck. With the Oster and others as it tries to pull food down everything just gets stuck.
Cook's Illustrated ranks the Vitamix as #1 and as a very close second a Ninja. And why, because they moved the blades all the way up the blender jar, thus eliminating any chance for things getting stuck.