problem with scag 48" walkbehind

[gdismine]

The engine starts fine but as soon as I try to engage the blades, they start to spin and then kill the engine. Is there anyone out there that can diagnose what the problem might be?

 

[mechanic mark]

Make sure underside of deck is clean.

http://www.scag.com/OPManuals/SW/2013SWOPMAN/SW_Book_03319.pdf see page 22

http://www.scag.com/manuals.html