AA+ landscaping -
There are a couple of things you can do to help resolve your issue. First, we recommend switching to "low sail" blades when bagging leaves. This will reduce the external air flow allowing (blow out) and provide better suction. You can get low sail blades from your Toro dealer. If this doesn't solve the issue to your satisfaction, you can also install a "leaf enhancement kit" which will provide a better seal around the perimeter of the deck. Again this is available from your Toro dealer. Estimated retail is about $90 (actual price is set by dealer). Just to be clear, if you opt to go with the Leaf Enhancement Kit, be sure to also install the low sail blades.
TURBO FORCE 48" Low Sail Blade part # 107-3193 TURBO FORCE 52" Low Sail Blade part # 105-7795
Leaf Seal Kit 48" TURBO FORCE part # 108-4091 Leaf Seal Kit 52" TURBO FORCE part # 107-1634
As you probably know, it's critical to have your deck height of cut set low enough to create a good seal between the grass and deck. If the deck is set too high air will blow out rather than create suction. Good luck.
- The Toro Company