The fuses used are pretty beafy, but when they go, the break can be quite small. I had the fuse go on mine, and by looking at it, you couldn't even tell. If you are getting a DMM you can test the fuse with that. Otherwise, I'd recommend buy a fuse and replace the current one. They are only a few dollars, so if it isn't the problem, it hasn't cost you much, but could save you money in the long run.