Passenger power lock switch problems

The passenger side power lock switch on my '95 astro will lock the doors but will not unlock the doors. The driver side power lock switch works fine and locks and unlocks all the doors including the passenger side. Can the passenger switch be opened and "cleaned up" inside as it seems to partially work. Can a new switch be ordered or does a whole harness(assembly) have to be ordered. What's the cost or is a junkyard a good choice.
This is a great website and thanks for the info.

Yes.

Yes/no.

I don't know the dealer cost, but a salvage yard is an option.

Yes.