I bought 10 Sega Genesis Controllers. Can Fix them?

I have a collection of Sega Genesis and SG ProPad Controllers that I do not know if they work. They are 3 button and 6 button controllers. Using an Arduino UNO I test these controllers and determine what is wrong with them for repair.
0:00 Intro
0:30 Setting up the Arduino
5:59 Testing 3 Button Controller
7:15 Testing 3 Button Controller (Red)
8:50 Testing Mad Catz 3 Button Controller
11:00 Testing SG ProPad 6 button controller
14:05 Testing SG ProgramPad 2 Controller
20:25 Testing SG ProPad
22:13 Testing 3 Button Sega Genesis
23:25 Testing SG ProPad 6 Button
26:22 Cleaning Sega Genesis 3 Button Controller
33:00 Comparing ProPad Controllers
33:40 Cleaning SG ProPad 6 Button Controller
41:50 Testing Controllers With My Sega Genesis
43:40 Streets of Rage 2
48:24 Streets of Rage 3
Link to Sega Genesis Source Code github.com/PathfinderCast/Seg...