Lens stuck on Mamiya RZ67 - Help?

I just attached a new 127mm 3.8 I just got onto my RZ, and after shooting a test roll the lens seems to be stuck. The lock ring will not budge, when putting it on it went on straight, so I don't think it's the threads that are skewed.

After researching a little I found out about the paperclip trick but all the info I've found on it seems to be for the RB. Any ideas about how I can get this off without risking something getting damaged? It'd be much appreciated!

Make sure to stoke the cocking/advance lever to reset the mirror and cock the lens shutter.

The lens won’t come off unless you do. See page 11 of the owner’s manual.

http://www.cameramanuals.org/mamiya_pdf/mamiya_rz67_pro-1.pdf

Lens removal is on page 12 of the manual

Forgot to add that the shutter was cocked. That was one of the first things I made sure of, not sure whats making it stick.

Managed to get it off with a rubber band for extra grip around the lock ring. Thank for the input!

whew!