May be George can answer this, the 2 modulation wheels ,are they part of the top cover or could they be removed ,the reason i'm asking is because if they're removable that means i could probably replace them with the new X1 joy stick.
eddy

Eddy, I don't think it's wise to do that kind of things to a keyboard; aside from the result (impredictable), it would lead to a HUGE loss of value on the used market.

... also remember that the max movement direction of the current mod wheels is North-South, whereas the joystick max movement is East-West. Unless you change the direction of motion when you install this, it might not 'look' right ... just a hunch.

Yes Eddie they are mounted on the cover.
George Kaye

(...thank God!)