I have several bollards outdoors and wanted to change this, the bulbs to LED. For some time the screws are now exposed to wind and weather and no longer rotate. Everything I've tried normal rust remover, WD40 ... Nothing helped. That's why this rust remover ordered in the hope that this helps.
Unfortunately, the screws are set still just as before. Despite multiple-usage and exposure can be. Too bad, at least in my case it was no help. For other applications it may help more.