An old impeller is like an ole tire, it can come apart very easy. A new one you have to turn it the correct way when you install it to flex the vanes or it will run against the direction and do the same. And....and ya gotta hook a water hose and foot cup to the motor to test it, if the alarm went off and you had that on there the impeller for sure is not functioning.

As for that leg, get two boards and some duct tape, place boards on leg and wrap with tape, then you can hop right along.