Still a newbie with questions.

I would like to rebuild this joystick and need to find a couple of parts. First pic is a blowup of the disassembled joystick and then a blowup of the piece I need to replace (as well as the missing spring). The other joystick on the cab I just bought is in great shape.

What is the name of this part, and is there anywhere that I can purchase replacements including the spring?

Thanks.