@Serle The best method would be to use some small scissors and carefully remove the bulk of the exuviae (shed exoskeleton). Slowly working closer and closer to the leg, cutting the exuviae. When you get near the stuck walking leg it may dislodge itself from the exuviae, or if left alone perhaps she can finish removing it. That would at least allow her to get around much better too.
I can see where I will have to aquire some smaller Mantid husbandry instruments , thnkz for the info. a little less abrupt than what transpired... Her leg is correcting slowly .