--- Fixing Bad Cartridge Slot Contacts ---
When you recycle some old game cartridge slot you always get from junk video games, and some times the contacts are not good because of corrosion.
But don't worry it's easy to fix
You will need a very fine sandpaper and a credit card (or any PVC card with the same thickness)
Cut the sandpaper to fit in the credit cart
Insert into the slot
Then make a right and left movement
Make sure to sand all the contacts
Clean the residual dust with a compressed air ou isopropyl alcohol and be happy with your new cartridge slot