I examined the situation and realized that the two plastic pieces at the back of the upper spray arm had simply oxidized overtime and weren’t sliding past each other as well as they did when they were new. I looked up the replacement part on appliancepartspros.com and easily found it. I decided to replace the main tub gasket as well. It’s quieter than it used to be and it works like new. Thanks, appliance parts pros! This is the second time you guys have saved my bacon!