The rubber drive coupling was worn out.

First, I want t say that I went out and bought a new blender since I believed that the previous one was beyond repair. It was other than a Kitchen Aid which did not perform as well as my previous blender.
When my new blender broke down after two weeks from the date of purchase, I returned it to the store and decided to make an effort to repair the one that has served me so well, over the years, having no idea that it could be restored so easily.
The blender was making green smoothies within 30 minutes from the time the part was delivered to my door.
Thank you also for the step-by-step instructions that made the task easy and swift.