Claber Multi Jet Sprinkler

Exactly what this product is supposed to do is impossible unless you have massive hands and a grip of iron. I had a sprinkler very similar to this that finally wore out after years of use, and bought this as a replacement. Simply put, I can't turn the ring to change the spray pattern. I lubricated it... no use. Slamming it with a brick worked once, jolting it loose enough to turn, but since then it's stayed stuck. Too bad... the one that worked that I can no longer find was great. This thing is junk.