I received a half-broken PS2 from a friend, it wouldn't read any discs. I decided to try to fix it, so I opened it up.
Because this PS2 (30001) was older than mine (50001/N), I didn't know the Power/Eject buttons were attached to the case, so I accidentally ripped the ribbon cable out of the board and the blue strip that keeps it stiff got caught on the bottom part of the case and ripped off , after performing open-laser surgery on the disc drive I decided to fix the ribbon cable by scotch-taping the blue strip back on (yes, I said scotch tape!), and to my surprise, it worked just fine! I still have that PS2, and it still works
I don't know if you'd count this as modding, but I was surprised it still works