Not many such handhelds are actually "serviceable".
What exactly needs servicing? If its more than a battery replacement the costs would probably exceed replacement of the PDA I suspect, even if it could be "serviced".
With surface mounted components in a miniaturised format replacement of a faulty PC board mounted item can be almost impossible. Servicing would usually be by replacement of the entire board, but that model is a bit old for PC boards etc to still be around I suspect?