My Smith 36 I bought when they still cost $68, that's bout 50 years ago. I just about ruined it by squirting WD40 into the works at the lifter. Now it's pretty gummed up in there and it kind of sticks. I'm not taking it apart though. I just deal with it. But I'd never squirt WD40 into the guts of any gun today. It hardens and things don't work as smooth as they did when new.
I have a pre-Model 10 that was full of petrified WD-40 when I got it. YUCK.
I just removed the side plate and blasted the heck out of the internals with Gun Blaster (same as brake cleaner) and let it sit for a bit before hosing it out with more Gun Blaster. Did that a few times, let it dry and oiled it up. Good to go.