Things You'll Need
Instructions
Unplug the Super Nintendo console, then attempt to turn it on so that any power that might be stored within the console is discharged.
Press the cartridge slot cover down with your finger so you can see the cartridge slot and the bay around it. Take note of the two plastic ridges on the bay wall behind the cartridge slot. These ridges fit into grooves in Super Nintendo games, but Super Famicom games don't have grooves, so they hit against the ridges when inserted into the bay.
Grab one of the ridges with a pair of pliers and twist it, breaking it off the cartridge bay wall. Repeat this with the other ridge, making sure that you break them off completely. Use a craft knife or other precision cutting instrument if needed to remove portions of the ridges that you can't remove with the pliers.
Insert a Super Famicom cartridge into the Super Nintendo cartridge bay to ensure that it fits properly and docks with the cartridge slot. If portions of the plastic ridges weren't removed and still prevent you from inserting the Super Famicom cartridge fully, remove the cartridge and attempt to remove the remaining plastic.