Small Engines (Lawn Mowers, etc.): Stack pulley keeps dropping down, briggs and stratton, center screw

Question
Hello

I have a Murray riding mower, model 40614A which has a Briggs I/C 12.5hp. Lately the stack pulley assembly has been dropping down its shaft. This usually ends up in a show of sparks! When I take both belts off I can easily slide the pulley up & down. How are these normally held in place - by belt tension alone?

Thanks
Cameron

Answer
The center screw that holds the pulley on is missing.  You will need to order the center bolt and washer from Murray...which is now Briggs and Stratton.  

You can look the parts up online at the Briggs web site and then order then as well.

You may want to remove the pulley and check the pulley key way and the crankshaft to see how wore they are.  You may have to replace the stack pulley if the internal key is rounded/ground off.

Let me know what you find.
Eric