Weird problem with step down ring

[Patrick Cooper]

Recently, I bought a step down ring to attach a 52mm ND filter on to a 135mm lens with a 58mm filter thread. It worked fine in the city for shooting video of traffic passing over a bridge. I haven't used it in a while and want to use it again. Problem is I just cannot screw this step down ring on to the lens anymore! I don't know what's going on. Logically, I'm using the larger diameter end of the ring but it just slides around. It will not engage with the screw thread on the lens. And I am rotating clockwise of course. I can screw the ND filter on to the other end of the ring no problem. This is really weird. Any idea what's going on?

Edited August 8, 2018 by Patrick Cooper