Removing annoying audio hum from Megadrive 2

Recently I got myself a PAL Megadrive 2, so I went ahead and bought a brand new RGB/Scart cable from Ebay. Not official, but the picture is pretty good. Unfortunately there is a hum to the audio which is a bit annoying, so I thought, this might be cheaply made.

So I go ahead and buy an (expensive) official MD2 RGB/Scart cable. I hook it up, and guess what, there is the hum again! So I do a bit of research and come across this:

http://www.retrocorner.net/index.php?Mods_/_repairs:Megadrive_2_RGB_cable_modification

Great I think, I'll open it up and cut the trace as explained there... So I opened it up, and find the trace is already cut O_O

So, er, what next?

Thanks!