I doubt that S&W will service a pre model 10, they tend to turn down requests for servicing revolver this old due to a lack of parts and liability concerns.
Stuck screws can be delt with. Sometime Kroil can help. Another thing that can help is using a hammer and a very slighty loose screwdriver to "shock" the screw after a good soak and then re-soaking. What this can do is cause the vibration to trigger that oil to penetrate into the threads via capilary action. In addition it can help to break the bond if there is some corrosion present.
Other times heat can be the solution, as in baking the gun in an oven set to about 250 degrees. BTW, this temperature won't have any effect on temper or heat treating because it's too low, you have to get to about 600 degrees F before any steel will start to temper, so it's completely safe for the gun. However, because you have to work while it's hot, you will most definately need some well insulated gloves to handle it.
Now, one warning. Odds are pretty good that you may bugger up these screws. To reduce the chance of this happening make sure that you have perfectly fitted screwdrivers before you start and I mean a fit close enough that they require a light tap to get them fully seated in the slot. I'll also warn you that if you use a pencil torch to heat the head of the screw, a last ditch solution, it's very likely that you will soften the head of the screw and that will leave visible damage even with a perfectly fitted screwdriver. You'll also want to have the gun very well supported while you are working on it, a lap won't be suitable. Personally, I'd take the time to carve a soft pine support to provide a fitted nest to hold the gun firmly and clamp the nested package to a bench while being very careful to not clamp so tight that the frame could get bent. Basically you want that nest fitted near perfectly to the entire profile from barrel to grip frame so that the forces you apply are distributed, then clamp your nest firmly to the bench and the gun very lightly into the nest. Also, if you have access to a drill press or vertical mill, chuck your screwdriver tip in either and use the chuck to turn the bit, that way you won't slip with your screwdriver and bugger up the screws.
Finally, I'd suggest that you try and track down some spare screws. Note, I expect that these screws are NOT the same size as what is currently used, S&W has a long history of making changes and I expect that screw sizes are one of the items that have changed over the years. So, you'll probably need to do a bit of hunting to find screws that will find your revolver. That source who was going to re-finish your gun may be one possibility, another may be hit the net, souces such as Numrich's, Brownells, or others may have the correct screws.
