Main spring repair
I'm sorry I don't have time to write a shorter letter.
I hate to tell you, but the clock guys are feeding you a line of BS about springs. I have taken dozens of them apart from different #10 cameras and can assure you they are one spring. I even have five or six brand new from the factory #10 springs and they look exactly the same.
I have had great success repairing broken main springs. It has been my experience that all the springs seem to break at one end or the other so shortening the spring is the most logical solution. It is not difficult to remove a mainspring even without the proper tools. A good pair of leather gloves and common sense as to restraining the spring when you uncoil it and it will easily come out. The most important thing is to not let go of everything in the middle of unwinding it.
Anyhow, the spring ends can be heated red hot for a couple of inches and then cooled slowly. This softens the metal and then you can easily reshape it, drill a new hole etc. You do not need to re-temper the spring as it is only a few inches in length and has no great overall effect on the amount of power on the spring. The inner part of the spring needs to be curled tighter so it can start to wind on the shaft so it must remain soft anyhow. If you look at an original spring you can see the color change where the tempering was altered on the ends.
If you decide to drill a hole in a spring that still remains tempered, it can be done with this simple trick - Use a drill press and a piece of blank steel the same size as the hole but totally flat on the end. When you try drilling the hole, it makes the spot red hot but can't drill through. This is perfect as it is now annealed and you can replace the blank steel with a drill and easily make the hole you need.
With your old spring out, you can dress it smooth with very fine sand paper and files. Make sure there are no nicks or breaks in the metal as it will break again in a heartbeat if left. Then wash and wipe it really good before installing. USE GRAPHITE. That worked for 80 years without problems and you can still buy it in any good auto parts store. Using grease, even Slick 50 poses serious problems when shooting in low temperature conditions and it sucks power out of the spring. I can't remember how many cameras I have fixed by simply washing grease or oil out of the spring and putting graphite back in. Unless you are going to Baghdad to photograph troops in August, use graphite.
Clock guys are OK people, but they think clocks and not motors. Motors are used in Cirkut cameras. Clocks must run with very little friction to maintain accuracy. Even the gears in clocks are different from Cirkut cameras as they are designed to have low friction but are not always in contact with their mate. The Cirkut gears are designed to run smoothly without interruption. They do not mix. Also a clock guy will repair a worn bushing by reducing the thickness of the metal with a special punch. Less surface area is again good for clocks but bad for fast running motors.
You would think the people you dealt with that repair victrolas would have an understanding of all of this but I guess not. Also, new spring material is readily available, the last time I looked is was around $75 for 500 feet. That's a lot of Cirkut cameras.
And yes, you have a Frankenspring, but that's not a bad idea to use three springs coiled together if you can figure out the amount of power it puts out. They would have to be three times thinner and that might be a problem. I suspect the spring would run nicer and longer, but not have much power. A good spring with a 64- 66 tooth gear will run the Cirkut camera for 2 and 1/2 full circles. Originally you could order a stronger spring but it was shorter too because it was thicker. I've seem them and wasn't impressed because they were also harder to wind.
You should be clever enough and brave enough to work on your own springs without getting one stuck in your forehead. I've been doing it for 27 years and still have all my fingers etc. The only time a Cirkut ever drew blood was my fault removing a broken ground glass. I might even hold a record by having removed springs from six #16 Cirkuts without killing myself and they are 40 feet long.
Hope this helps,
Ron in Alaska