On the B&S Sprint 375, the governor springs are located under the air filter canister. If you remove the canister (single screw on the top), you should have easy access.
To know what they look like, go to the following link:
http://www.briggsbits.co.uk/acatalog/copy_of_Quantum.html
The "idle governor spring" is the 12th item listed. The "throttle main governor spring" is immediately below it.
You can also download an engine operators manual (.pdf) and/or an illustrated parts list at:
http://www.briggsandstratton.com/display/router.asp?DocID=78498
Note: to download the docs, you'll need to know the engine model number first. Click here to find out where the model number is on your engine:
http://www.briggsandstratton.com/display/router.asp?DocID=65864
The other thing to check is that you have put new fuel in the engine - and you may even want to add a fuel stabiliser (the B&S product is called "Fuel Fit").
Hope this helps!
Brad
April 2007