Craftsman gas pressure washer bogs down when spray wand trigger is released. If trigger is held open it works fine & engine runs at all speeds. Unloader needs to be adjusted but don't know how to do it. Unloader has large spring surrounding slotted stem adjustment screw.

Hi,
You are correct that the unloader is not working, but without a model number it is not possible to know who made it for Sears. You can go to the Sears parts site with that number at:
http://www.searspartsdirect.com/partsdirect/index.action
Peace,
Clarke

Many times it just takes a good cleaning and a lub with lithium. How to Fix a Pressure Washer (Part 1 of 2) - YouTube (http://www.youtube.com/watch?v=Qmrhgq22ASI)