TLM corkscrew setpieces

Tonight, at TLM, one of the giant corkscrews (for lack of a better name) was missing actors during the whole show. During both Under the Sea and Kiss the Girl, the corkscrew coming from stage right with the arms that come from the top had two actresses, as usual. However, during both songs, the one from stage left with the arms that come from the bottom was empty. I remembered that they both used to be used, and I have found video to back it up from GMA. My questions are if this has been happening for a while and why? During Under the Sea, I originally just thought that they had missed their queue, but I was puzzled when they did not come out during Kiss the Girl either. Does anyone have any answers?

The stage left one was missing actors in last Sunday's matinee as well.

Probably something happened to the unit to make it unsafe.

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I do know that for the first preview, that same set piece did not appear the entire night as well. i'm a little surpised that something happened again.