The windscreen wiper mechanism turned out to be in better shape than expected. Although heavily rusted all over, definitely not beyond repair. After I disassembled the wiper motor, I cleaned and checked the armature for continuity, replaced the carbon-brushes, greased all moving parts and reassembled the unit. Note that 99% of the wiper motors will be 6-volt, if you plan to convert to a 12-volt electrical system; have a read through our 12V Conversion for more information.
The wiper frame was sandblasted, primed and painted. When reassembling, make sure you replace all the clips and lock washers; most of them will be worn with age and should not be used again. Carefully grease all the moving parts of the mechanism so you can enjoy squeak free windscreen wiping.