Despite pre-flight checks not revealing any issues with the sensors, gyroscopes 2 and 3 gave "erroneous but similar inputs" as the plane took off. While gyroscope 1 provided correct inputs ...

[Curious Marc] has an Apollo-era gyroscope but isn’t quite ready to put it through this paces without some practice. So he borrowed a 1949 vintage Sperry C5 gyro and did some experiments with it ...