In order to test a cartridge fuse, you will need a multi-meter. With the tester on turn the dial to ohms on a lower setting. Place one end of lead on either side of the fuse. If the fuse is good, the tester should have little or no resistance showing on the meter. I tested several today and they all measured 0.5 ohms. If the fuse is bad, you’ll see an infinite reading, meaning the fuse link is blown.