This mechanism has overload coupling inside. When mechanical overload occurs the coupling may klick. Else doors are jamming so coupling is set too low. Check doors and if they are easy look at coupling - it has spring and screw adlustment at center of linkage drive whell.. I don't know Your model but in Ouverture it is easy to reach. But don't try if you are not experienced (You didn't damage minimum 10 sets in life :).