I have a 5 year old GSP who I have force fetched. In the last year or so she has started to not release bumpers, birds when I command her to release. Instead she will shake and then bite down really hard so I cant remove it from her mouth. She may even start pulling away from me. she goes out and brings it to me perfect though. It has gradually gotten worse. Iam wondering what i should do in this situation? How can i get her to open her mouth? is there a technique i can use? thanks