You certainly may be right about the door window lifter mechanism being
in need of service (lubrication of lifter parts, channels and slides),
but I would certainly take the few moments needed to service the door
switches too. Simply lever the switch assemblies out of their sockets
and gently disconnect the wiring harness connections. Hold the switch
assembly over a paper towel so that any parts that fall out will be
easily retrieved. Very gently lever the sides of the switch body out
until the rocker can be lifted away. It is best if you grip the
assembly with your left hand keeping light pressure on the rocker with
your left index finger while you lever the sides apart with a small screw
driver or pen knife with your right hand. If you VERY gently lift the
rocker you will be able to observe the positions of the rocking contacts
and the spring loaded balls. Make a mental note of it all. Take
everything apart and clean all with a light solvent such as alcohol. Look
carefully at the contact surfaces of the contact rockers. You will find
one or more to be burned or pitted. Dress each with the finest abrasive
that you can find. You might use the striking surface off of a match book.
Then look down into the cavity of the switch assembly. You did clean it
up too, didn't you. You will find at least one burned and pitted contact. It
is sometimes a real turkey to get down in there to dress these contacts,
but do the best that you can. Sometimes it is best to use a very sharp
small knife to "wipe" the contact surface. Remember, the smoother the
surface the longer lasting this repair will be. On some switches there
are also electrical contacts made at the center of the contact rocker.
These surfaces will be brass and will be more likely to be burned away.
If you can, try to use your knife to scape away any obviously burned
areas leaving as much clean metal as possible. During reassembly use a
little dielectric grease at each pivot point for both the contact rockers
and the actual thumb rocker. Make sure that each little ball is clean
and lightly lubricated. If your switch has small plastic plungers instead
of balls try to smooth out any flat surfaces with your abrasive. Make
sure that the small springs are free in their cylinders. Place the
contact rockers back into position. I usually try to "spread the work" of the t
ends of each rocker with the most damaged contacts of the switch body.
Use just enough lube grease on the balls to make them stick to the ends
of their spring houses. Hold the switch body steady against the table top
as you lower the rocker unit down into position. Very gently press the
rocker into its pivots in the switch body. Test by GENTLY throwing the
rocker first one way and then the other. If you encounter any significant
resistance STOP. It probably means that a ball dropped out of position
during assembly. Take the switch back apart and correct the problem. Once
the switch feels right reinstall it adding a little grease to the
contacts for the wiring harness. During my 35 years as a
"Mercedes/Volvo/and others" technician I must have saved customers
thousands of dollars in non-replaced swiches using this method.
Good luck. Jack