The handle on the right hand steering lever should have a pivot point to control the aux. flow. There should be a pin through the handle and the lever keeping it solid when not in use. Another thing to look at before attempting to run an attachment is the position of the spool on the aux. control valve. There should be a sticker somewhere near where your right leg sitting in the machine telling the position for motor or cylinder use. I don't remember the proper positions off hand and don't have a machine in the shop to reference. Make sure that it comes with the proper brackets and the proper mounting plate style. The L785's had a wedge setup that slid into a set of ears on each side of the attachment, but there was an update kit at one point that adapted it to use the new style attachments.