That sounds more like one of the ratcheters moved too far and allowed the central spindle to slip past it's limit. That actually sounds like it could be fixed. I would offer to help you out and take a look at them but I am currently working on someone elses shifters right now and I want to finish those. If you are feeling adventurous try taking them apart and perform a reassembly. Otherwise If you can PM me if you want to try and work something out with fixing them.