IF Windwave distributor is still alive and kicking then they will no doubt hold stock of old manuals, possibly even the springs otherwise try UKBikeStore.
http://my-sport.spb.ru/manual_1/2001%20 ... op-off.pdf
For changing from 130 to 100 or the other way around, you must change the main springs and the topout/rebound springs, as the other posters said.
There are 2 rebound springs but you must take out the Pumping rods to acces them (see manual in the link above).