Usually there are two small screws that hold the handle on. If you take those screws out (drain tank first) you will find a wavy spring washer, this spring washer pushes the handle against a 4 hole rubber bushing. If you bend a little extra kink into the spring it will push the handle in harder. Also, make sure the contact area of the handle is flat and smooth, if not, file or sand it. One other thing besides rebending the spring washer and resurfacing the handle is pulling the rubber bushing out and flipping it over, good luck.