Just taking the gun apart and putting it back together will not cause problems with the lockwork. If the action is smooth and the timing is correct then the lockwork is good; it's as simple as that. As for the screw, that's easily dealt with; replace it or clean it up yourself and re-blue with some cold blue.
Contrary to popular opinion, Colt DA revolver lockwork is NOT fragile at all. The "test" that people do for timing will tell you if timing is "book perfect". News flash, most Colt's DA revolvers came out of the factory, not in "book perfect" time. That doesn't mean there's a problem, just means it's not as perfect as it could have been. The design is such that even when timing isn't perfect, it will still be in time and work correctly The first notch on the pawl is where you get your "book perfect" timing, but the second notch on the pawl is the backup to ensure that when the gun goes off, the cylinder is aligned with the throat even if the first pawl doesn't do it's job absolutely perfectly.
A S&W is much less sophisticated, it's either in time or it's not; there's no in between. The Colt's can have varying degrees of timing and still work perfectly. The problem is, there aren't a whole lot of people who understand the Colt's DA revolver very well. Even the "experts" will tell you if it doesn't pass the "book perfect" timing test, then it's out of time. But most of those "experts" also sell services to put your revolver into perfect timing...you do the math.
This two cam pawl design makes the Colt's DA revolver a bit more reliable in nasty conditions than the S&W. When the US military did tests between the Colt's and S&W, both before the turn of the century and for the acceptance of the 1917 revolvers, the Colt's was always the more reliable revolver. The difference isn't night and day, both S&W and Colt's DA revolvers were considered acceptable in the reliability department, just that the Colt's had a slight edge when things got nasty. Neither are as reliable as a Webley in nasty conditions.
With a S&W if the timing is bad, you can end up shaving lead or even have a situation where the revolver is unsafe. I hear talk all the time of Colt's DA revolver that are "out of time" yet you almost never see one that's shaving lead or unsafe. It's just that the timing isn't "book perfect". Most are ignorant to the fact that the gun is still operating within normal parameters.
And that goes for all of the older Colt's DA revolvers. It's rare that I've even seen a Python that has "book perfect" timing, yet Colt's sends them out. Why? Because while not "book perfect" the timing is still right.
When is timing off so far the gun is unsafe? When you pull the trigger all the way to the rear and the cylinder is not locked into the locking bolt. At that point you have a real problem.
My Colt's Cobra is only "book perfect" on two chambers, yet it shoots perfectly, safely, and quite accurately. There are no signs of shaving lead or anything out of the ordinary whatsoever.
I hope you find that helpful sir.
Kevin