Fujimo, I have an all digital design in mind that will also weigh the shaft before spine testing it. It will basically work like this: turn on or zero the scale, insert shaft then hit a button and the spining operation starts. At the end the weight and spine are displayed. This will work like no other tester you have seen - if it works at all.
Don't wait up for one, this design is in my head and will require circuitry and code development and is not an active project I am working yet,
Stringstretcher - yes it can work manually. I think some sort of block that fits between the weight and the top of the main support will hold the weight up when installing the shafts.