Oh, that garage sale blender struggle is too real! I had a Cuisinart that was acting weird until I found the manual. You can check
https://manuals.online/cuisinart for a ton of their blender manuals. Look for the model number on the bottom—mine was a SmartPower, and the guide showed me how to fix the blade assembly. Took a bit of tweaking, but now it’s blending like a champ. Should sort out your smoothie disaster too!