I had the same problem but the solution is to do a search on the net for the briggs & stratton Operating and maintenance instructions for the 10D900 engine and download the file 22938.pdf. Its shows the spring connections in the setting the throttle section. It works even if you have a fixed throttle setting. Mower now running best its ever been after new diaphram and spark plug.
Happy Cutting
Gordon - Burnhervie Aberdeenshire, April 2009
