if the black chute on the side flips up, flip it up and find a way to fasten something inside it (on what would have been the underside) that hangs down and covers the opening. You can put two pieces of thin plywood held apart by a strip that slides over most of it with a pin that goes thru the wood and it, to keep it from accidentally coming free, and a bunge cord or small piece of small cable or chain to hold it up while the fixture is on it and hanging down. It can be a two pieces of stiff flat plastic with something to space them apart so they can drop on the chute. When done remove the bunge cord / chain, pull the pin, pull it off and flop the chute down again. All you need is to divert the clippings for a moment.