My GE Toploader washer spins but doesnt agitate.

My washer fills up, spins and drains right, but when it comes to agitating it does nothing. My wife started noticing that the clothes still had soap on them after a cycle. I took the front panel off and the motor seems to be working fine, but when the agitating part comes it doesnt do anything. I even took that middle agitator off to make sure there wasn’t a sock or something stuck in it. One friend says its a "knuckle" of some sort and another guy thinks its a switch. If you guys need any other info let me know, Help please!

by the way this washer is 4 years old but has only been used about a year i had it storage for a while but ive been using it since about june of last year dont know if that helps…