Today I repaired these 2 GameCubes with “No Disc” error. Cleaning the lens did not fix it, so I slightly raised the voltage to the laser and it works now. No cost fix. Super happy I can now play on my HDMI TV and capture game footage. (The 2 I fixed have Digital AV out and I have a GCHD Mk-II)
For anyone interested in the fix, here is the ifixit page with instructions: https://www.ifixit.com/Guide/Optical+Laser+Lens+Power+Adjustment/1484