Kitchen Aid 550 HD - the bowl holder does not stay up or lock in the up or mixing position tightly. It sags about a 1/2 inch and therefore the mixer blades do not hit the bottom of the bowl as they should. Did the dime test and tried to adjust, but it is adjusted as far as it can go and there is way too much flop like the gears or track is stripped. Is there a repair kit or some parts that I can replace to remedy this?