Correct Screwdriver:
 

Not a restoration, just wanting to clean. If someone could direct me to the proper screwdriver or set, I would purchase one. I have a Wheeler set but the correct tip isn’t quite long enough to completely fill the slot, it’s either correct or it can’t be used. A capable person would just make one, however I am not that person. Please point me in the right direction.

A kind and generous member is mailing my request. There are many good people here.

For future use, you can do this yourself. I learned by watching a couple of YouTube videos; buying a few trashed-out screwdrivers at yard sales and fitting them myself. IMHO the real key is to pay attention to fit first, then heat treating second. For all but the most mangled bits, forget about grinding wheels and learn to use 2-3 medium to fine flat files. Practice on the most trashed-out drivers first. Once you achieve the precise fit, pay close attention to tempering and cooling. This will ensure that you won't break off any bits on engraved screws, the ultimate bummer! I have successfully ground and filed a couple of old Sears Craftsman drivers to fit the ultra-thin and fine screws of the Browning Superposed trigger guards and forends. White knuckle, yes, but learn by doing and proceed with caution. There is great satisfaction in fitting your own turnscrews to a particular gun. Should also add I did it to one to fit most of the screws on my 1897 AH Grade 16 gauge 0-frame Parker. As the Germans say, "Keine Angst!"

Buy the complete set from Brownells, also the additional thin blade set, and the Browning A5 set (handle plus five extra-thin tips) and you will always have what you need and no buggered screws due to not having the correct one (but doesn't mean you can't still bugger the screw). I know.

Easy answer: As Jerry says, Brownells set. No one tops that in my book

Dont be surprised if the hammer does not come off after you remove that screw.

Do what you want but considering the high condition of that gun, I'd clean underneath that hammer without removing anything. It's possible you might damage something and that hammer is a wedge fit on the axle(?). Every time it gets removed and replaced the potential for it to get loose increases.

Sound advice for sure, best to leave well enough alone. “Do no harm” resonates with me. If it was broken internally it would require attention. Since it functions well it would be advisable to not take unnecessary risks.
Thank you George!

Just for future reference, the Brownells set and the extra thin blade set will handle most situations. Dan Rositter advised me to get a couple sets of the Grace hollow ground with the wooden handles. He said use one as is and if you need a special width driver to grind one from the second set on a drill press with a hard Dremel stone. It works slicker than goose dookie.

A couple of tips from over here:
When I look at screwdrivers at yard sales, I look for wooden handles, though there are some good ones with plastic handles. (usually not clear or see thru plastic)
With estate sales, I can usually tell by taking a glance around the garage/workshop area if the previous owner believed in high quality tools. If so, look deep.
Also, solvent and compressed air can work wonders.
Gloves and eye protection, of course.

Pipecleaners are an excellent utensil to reach in difficult areas.

You don't need to remove that screw to perform a proper cleaning.

Yes, I understand the sideplates can be removed with the hammers intact by removing the left plate screw. As of yet I haven’t done that, though I want to. The left hammer lets go with minimal trigger pull, very similar to a target rifle. I imagine a thorough cleaning of the lock may illeviate this. I read somewhere that the hammers should be at full cock before removing the plates. When I muster up enough courage to proceed I will remove the locks. I’m slow but methodical. So far, just slow.

Which set covers most (if not all) Parker screws and pins?

Brownells is usually considered the best hands down , but they’re also the most expensive . I’ve got some Brownells but a couple years ago someone brought in a large like new set from Wheeler Manufacturing and since it was only $20 it came home with me . Certainly not the best for professional use but just find for my limited needs .

Dido solvent