If the connections are still intact clean the oxide with a solution of baking soda and water. Use a flux brush. After that, rinse the baking soda off with water. Don't get nuts with making it pretty we just want to stop the corrosion. Use the same brush several times rinsing it with water between steps. After the leads are dry cover the bare parts of the wire with clear RTV silicone sealer.
The above will not likely restore the operation but it is the right thing to do.
The service manual is here: https://www.vinylengine.com/library/denon/dp-75.shtml
With an oscilloscope observe the signals from the heads at each stage until you find the failure then investigate the cause. Note that there are two heads each with its amplifier to resolve the direction of rotation.
bendoggie wrote:I dont see how i can clean that without cutting off the wires and resoldering them. Will the heat damage the head ?