I have a 1980 633csi with wipers that will occasionally not respond to
the switch on the steering column.  After not working for ten minutes,
they will suddenly start up again and work normally.  I cleaned the
contacts to the motor, replaced the fuse, took apart the motor,
replacing both wires to the brushes, and also the ground coming off the
connection.  I took apart the "rotary contacts" at the head of the
motor, and cleaned them, and lubricated the rack and pinion gear
running the rotay contacts.   I lubricated all parts of the assembly
with solicone spray. Things seemed fine until the next day, when the
wipers quite during a drive, and then after 10 minutes started again.

Help!  Is there a relay? I don't see one in the fuse box, and the fuse
is fine as the washers work fine when the wipers don't.  Advise would
be appreciated.

Paul