Disc drive not working consistently

Recently, my Wii's disc drive is starting to not function. One day, when backing up the system with BootMii, I press eject to skip verification (Okay, maybe I shouldn't have), only for Mario Kart to eject. I try to put the disc back in, it won't. It works fine the next day. Today, I eject Mario Kart and try and put in Mario Galaxy, but the disc gets stuck again. My dad takes a look, and the MK disc goes in fine once, except the wrong way. He took it out to put it in the right way, and it wouldn't go in. The hardware is unmodified, and I don't think BootMii or HBC has anything to do with this, being software. Is there an easy fix for this? We've had it for a few years, so it's probably out of warranty, and I wouldn't feel comfortable cracking open the console to find the problem. What can I do?