Windscreen Wiper Mechanism

If there is a tech forum pls redirect me. The spindles on my front wiper mechanism have almost died, especially the central one. There seems to be nonparts available. Is there a part available or a modification I can make? Thanks in advance.

Can you elaborate? Do the spindles move but the wiper arms don't? Or are the spindles not moving?

I would remove the wiper arms, 10mm nut after removing hte cap, then clean the splines on the shafts and replace the arms and tighten the nuts, the arms are aluminum, and the shafts are splined steel. The dis-similar metals corrode, and the wiper arms spin on the shaft.  Cleaning the splines on the post with a brass tooth brush and replacing the arms and tighten the nut until the arms can't move on the shaft.

Thanks guys. The threads are quite worn and it has left play where the drivers side meets the scuttle pannel, which is letting in water. The blades themselves move okayIsh, but not on intermittent, though the motor is working fine. I have got a mk2 upgrade motor to put on but the passenger wheelbox/spindle is very weak.