Now I have the Pegas Steel in my hand,.. an easier way to make the mechanism cater for shorter necks is to use a 3mm thick washer with 2 holes drilled and locate it between the body and the 'Bush Steel 15' shown here as part 15
http://www.pegas.lt/en/19-pegas-steel
I tried a temporary couple of plastic washers and it worked.
Of course ordering the adaptable Pegas Steel 1881 would be better
