Retighten the blade

Unplug the tool from the power source. Place the LARGE L SPANNER into the blade SPINDLE CLAMPING SCREW and rotate it counterclockwise to tighten it, while holding the SMALL L SPANNER stationary in the center bolt hole on the back of the spindle assembly. Remove both spanners after the saw blade is tightly attached. If necessary, remove and reassemble the blade.

Possible cause:
Blade is not tightly engaged with the spindle