Does anyone  know how to re balance the radial arm on the CDM4?

I picked up a BC 25000 last weekend. I notice that on the CDM4 in my
BC9500, the arm floats in the middle of the arc path.

On the 2500 it is floats closer to the outer path of the arc (ie further away from the the center where the turntable motor is.) What happens
then is that at the end of a CD or when I stop the CD during play the arm will disengage and fall away from the turntable motor and hit the
housing of the mechanism making a "click" sound.

If you gently lift the optical pick up with your finger and move it to the center of the mechanism and then let go, it should return to the center without striking the body of the mechanism  on its way down. (at least this is what it does on my 9500).

Any ideas?

Thanks in advanced,

Derek