philkelly said:
A spring from a retractable biro is an adequate replacement for the external "spike" spring. A whole biro spring is too powerful - it pushes the skate so hard that the wheels can lift from the track. Two thirds of a biro spring is about right. I have not found an adequate replacement for the "internal" spring, which has a much smaller diameter. I have replacement skates on order from Dragon which come with these springs. If there is a source of very small diameter springs I too would very much like to know about it!
Thanks for the tip, Phil, that's very useful. Since my original post, Walter Turner (walts-playmobil) has contacted me to tell me that the Playmobil springs are different from the LGB ones, but he has some spares of them and will send me some.