Hi, I suffered with cording badly and saw a physio who worked on it and it did go, took about 6 sessions but each time it got easier, you need someone who is experienced in cording - they are about.
i don't know about a massage machine but wonder if you might benefit from a physio assessment? I had cording early on but got through it with gentle stretching and got full movement back but, at a recent physio assessment prior to starting Pilates I realised that my range of movement has reduced. Now doing gentle stretching to try get it back. Do ask your BCN to refer you to physio for guidance.