Having finally worked out how to play the buzzing rhythm sound from the soundfont file on the attached mobile phone MIDI player, at present by pressing a button on the handle, this means I can now replace this button in theory at least with some form of crank handle.
The crank handle is low cost and intended for a fishing reel. I have attached it to a motor which has a reduction gearbox. I had to buy 3 motors with different reduction ratios before I found one with the right amount of mechanical resistance to turning. In this video update I show each motor and also show how I can make an attached pager motor buzz by turning the crank. As the handle on the current Digi-gurdy can slide fully out and is attached electronically to the main body via a headphone plug, this means it could possibly be replaced by a crank module with no modification of the main body of the device, for those who wish to try it. More work required here but clearly this has potential. I will see how I get on and show the results in the next update.