Does anybody know if you can open up the 87 Sierra light / wiper switch unit?

I've opened, cleaned and regreased the full beam/indicator one, but can't figure out how to get into the other without destroying it?

do the stalks work ok?

I think the switch is dodgy. If you waggle the stalk it intermittently shorts between pin 30 (live to stalk) and pin 58 (output to sidelights). Thought it might just be corrosion, if I could just get in and take a look.

Drill a 1/8 th hole in the cover squirt it some Servisol switch cleaner operate it a few dozen times and hey presto I'm your mothers brother.
Cheers,
Bob

Contact cleaner worked on mine when they played up after they had a good soaking in the rain.