i have a 2006 slk 280, it has about 24,000 miles and recently i noticed when i try to drop the roof to a convertible everything seems to work fine, windows begin dropping the trunk starts to go up, i can hear the pumps working just fine then it just stops i am still hearing the hydraulics as if it is trying to pull the remaining top down but as i continue to hold the button in the down position nothing is happening any suggestions.