ATTICUS: I have popped the side plate on more than a few SW's. If they have never been off, you usually find a black goo in there that looks like dirty syrup. The powder blowback saturates the oil over time and oxidizes it. You could try taking off the grip and hosing the insides with brake cleaner through the slot in the frame....problem is, then how do you re-lube it? Could shoot in a spray lube. That method is probably better than nothing, but proper cleaning is best.
They are not that hard to clean if you use the right tools and know how. I recommend Kuhnhausens SW revolver manual (about $18 from Brownells). In a nutshell: you need to take off the grip (usually pretty easy but may be stuck on a bit). The three sideplate screws can be tough to take off the first time. You MUST have a good screwdriver with a hardened blade that fits the screw exactly. And, the screws are a funny size... not real wide, but thick in the slot width. Most people stick a screwdriver in there and tear the head up.
The best tool would be to get a screwdriver tip set with lots of tips and a driver handle. If you don't find an exact fit, file one of the tips down. Use penetrating oil into the screws. Lay the frame down on the side and apply pressure straight down as you turn so the screwdriver can' t pop out.
Once the screws are out: the sideplate is usually wedged on tight (by design) DON'T PRY ON IT! Use the wooden end of a hammer or the plastic handle of a screwdriver to whack the frame (handle area) repeatedly about 1" below the sideplate. Hold it over something soft so the sideplate won't fall on the ground.
Sideplate off: hose down everything with cleaner spray (brake cleaner works great) and apply good oil where needed and a good lube like Tetra Lube where you can (especially on hammer/sear faces).
The transfer bar (the piece that is loose) has to be correctly positioned to get the side plate back on. I use a little blue Loctite on the screw threads so I don't have to over torque them going back on. I recommend the Kuhnhausen manual as that will show you how to take out the hammer and do a more thorough cleaning.