It was reported that the hot cell turntables would not rotate and the access hatch could not be operated. The turntables' elevation motion was working normally, and other cell functions were working.

Upon investigation, after going online with the PLC and checking the interlocks for the turntable, it was determined that motion was being prevented because the turntables were in the "critical position" in which they could interfere with the access hatch raising/lowering. However, the access hatch was fully closed, so this logic should not have been actively preventing motion. After inspecting the target access hatch limit switches, it was determined that the upper limit switch's Normally Open contacts were behaving normally, but the Normally Closed ones were not. When the switch was toggled, the NO contacts did not switch over. Thus, the sensor was in an unknown state causing conflicting logic in the PLC (the program thought the access hatch was in an intermediate state between opened and closed, thus preventing motion... and the access hatch could not move because the turntables were in the "critical position"). After testing the switch multiple times, jiggling the wiring/contacts, and rewiring one of the screw terminals, the NO contacts started working normally again. It is suspected that a wire was loose. 

The issue has been resolved and tested - the access hatch logic is functioning regularly and both turntables can fully rotate and elevate.