I like to point out a little bit of possible misinformation:
I should note that some limited elevator trim change could be done by messing with the centering board that had contacting wipers that controlled the motor for centering. I think this was used to have additional down trim for inverted attempts, but am unsure of this point.
First,in a 10 channel "reed" airplane the elevator had two servos connected to the elevator push rod. The primary elevator servo would neutralize when the leaver switch was released. The "trim" servo had one pair of "followers" lifted off the arc foils in the servo which disabled the neutralizing function. Second, silk, and not nylon was by far the most common covering material of that era. Finally, the first mylar covering film was Monokote with a sticky adhesive. That only lasted a short while (about a year or so) before the formula was changed to have the adhesive heat activated. The film did not change. Years later Econokote was marketed as a low temperature film for foam airplanes. Phil Kraft did designed the Ugly Stick, and it was published in Grid Leaks, but the first kit was a product of Jim Jensen, so it is known as the Jensen Ugly Stick. At one time it was so popular that Jensen marketed separate wing kits, and fuselage kits too. With the popularity of the heat shrink films, which resulted in a lot of wing failures, Jensen modified the kit to include sheer webs between the spars. Silk is stronger then film. I had several silk covered Ugly Sticks, and I built a Veco Smog Hob for a friend over 50 years ago. As I recall we beefed up the wing, because they were known to fail. The Smog Hog is a very capable airplane even if it looks more like one of today's trainers. If I built one I'd have to cover it with silk. It would be a great trip down memory lane!