NOTE: I am nowhere near the first person to do this. I got my steps for this from http://users.adelphia.net/~kiltz/.
Anyway, modifying your beatmania controller's turntable will allow it to move more easily. The increased sensitivity will especially benefit pinky scratchers who find that they aren't moving the turntable enough due to it being too stiff, but this mod is for everyone who thinks that their turntable would be improved by it being looser.
Step 1: Gather materials
You will need the following:
Phillips Head screwdriver (I used the one from a cheap multitool)
Something to cut on (not pictured. Be sure that whatever you use won't get punctured if you press down really hard (the newspaper I used unfortunately didn't work so well).)
Small container for the screws (also not pictured)
Step 2: Eject the keys
Push in that black button on the back of the controller, and slide the keys out. Put them aside.
Step 3: Unscrew the bottom
Use your Phillips Head screwdriver to unscrew all the screws from the bottom of your controller. You should put them in some sort of small container to keep them from getting lost. After unscrewing it, set your controller's bottom aside.
Step 4: Remove the turntable
Turn the top part of the controller upside down so you're looking at the inside. Unscrew the screw in the middle of the turntable assembly, and set the top aside. Be sure to put the screw somewhere safe.