What are you doing continuing to turn a screw if you are stripping it? I'm sorry to tell you this, but if a screw strips, it's a user error, not the manufacturer's.
Don't worry though, Flow has excellent warranty service. Just contact them and send it in. They'll fix it for you. Also take some time to look through the user's manual next time you have a question like this. The manual outlines how to adjust your equipment.