My Delta Bathroom Faucet is leaking. So, I first took off the handle. Then, I used the special forked tool to try to loosen the plastic notched lock ring that fits just inside the threaded body that you take off to change the two little springs and rubber inserts inside to stop the leak. The only problem is, the plastic notched lock ring will NOT loosen up. I have tried PB Blaster as well. What can I do to loosen this lock ring so that I can remove it and the metal threaded body?