Simon at Sifab is your man, I was told the factory have none in stock but worth checking. Simon can repair or manufacture to higher spec. I believe the bottom wishbone has a bush in it for the stub axle that is bonded to it, I think Simon said he can remove it and bond in a new one. The fronts on S1 have lower wishbone and top is canterlever arm like on a race car. I presume the rear is two wishbone of sorts fixed in the cassette that bolts to the chassis.
