how odd, we have no issues with ours, in fact i would say that we have the easiest time getting them back ON! ha
i never found them to be a bad design, however i can understand frustrations like that on machines. i like the covers, but yours is new and there are a few tiny cosmetic changes between those and the 2008 models we have. curious if there is any difference, doubt it, but ours are like a car battery cover and holder with the long rods with a hook on the end to conect to the machine, and the other end has threads and an nut holding a metal L shaped cover. try some locktight for the threads if yours is the same and i am sure it will stay on if you give it a good crank after application of that
all is fair in love and grass!
Man, it smells like sheet, do you smell that!!