This refurb was inspired humanz recent post about motor magnets which had come apart from the wiper outer body - but I didn't mess with the brushes/springs and the motor stayed mounted on the gearbox mechanism/wiper mechanism.
Try this to vastly improve wiper performance.
You don’t need to take the motor off the mechanism to get much better results, you don’t need to disassemble the wiper mech or the inner gears - you can do all of this with things still in place but you do have to unmount a few things - cleaning + lubing shafts/tubes optional but might as well while you're in there.
Take wipers off, remove scuttle panel
Undo large single bolt to release wiper motor + mount/bracket off the mount plate attached to the body/scuttle
Loosen mount/bracket + motor off rubber buffers
Now you can access the two small bolts holding the motor ‘can’ or body/housing to the motor mount/bracket + gearbox mechanism
Slide outer motor ‘can’ or body/housing off inner armature/shaft which stays attached to the gearbox mechanism + motor
Clean thoroughly inside body, make sure inner magnets are attached to the inside of the body/can.
Lube the bearing that’s recessed into one end of the can/body.
Get rid of corrosion and polish the outer face of the armatures - the surfaces which pass close to the magnets inside the body.
Give the outer surface of the commutator a good clean - the smaller copper band on the shaft
Undo x4 small bolts holding front plate of motor mechanism. On inside of the front plate you’ll see three straight contact springs - bend them away from the plate - they’ll push more firmly to the contact disc. Clean them and the contact disc.
Use your preferred lube on the gears. make sure they’re clean and free and
Put the body back on the motor with the two small bolts.
Put the plate back on the gearbox mechanism.
That should be a total of six small bolts.
Put the mounting bracket back on to the rubber buffers and put the large single bolt through the mount/bracket and into the mount plate attached to the body/scuttle.
Test the wiper shafts are turning OK.
You should see a very clear improvement in wiper speed. If you don’t, you might have to go back in and take the motor completely off the gearbox mechanism to check the brushes, springs and wire on the commutator. Can’t advise on that but doing everything else above gave perfect wiper operation after suffering with slow wiper speeds for a while.
Also, while you’re in there, you might as well unbolt the mounts/tubes off the mechanism/shafts and clean inside and lube them as well. There are some C-clips and washers each end of the tube if I recall.