Had the exact same problem on an 8820, It's awkward but if I remember right take two 9_16 wrenches (might have been 1_2") and there is a couple of bolts below the throttle lever, where it pivots. Reach down beside the lever, you don't have to take the console apart or anything, they are hard to see and hard to get wrenches on. I think there is a friction washer or something in there. Anyways to make a long story short tighten those two bolts snug and it should stay. They probably just got loose over time.