I replaced the cap screw and the bowl to get a new combination mechanism, which I hope will keep the bowl locked into place even if the dough is firm. I also ordered replacement screws, not knowing if the original screws would be damaged when I removed them. They were not and I will be returning them, if the postage isn't greater than the value of the screws. The new bowl and locking base are fabulous. It was when I made an old favorite recipe that I knew the base no longer held the bowl firmly because that dough is firm and the bowl was thrown off the stand repeatedly. I stopped trying to make that recipe and replaced the bowl and locking base. Now it works beautifully. Also, both the cap screw and the bowl have to be replaced at the same time because the old cap screw will not lock the new bowl, nor will the new cap screw lock the old bowl.