You can replace lua51.dll in 1.6.2 using the version from 1.6.1 and check if you have scrollbars.
celestia 1.6.1 needs lua5.1.dll
celestia EP V3 v5229 needs lua5.1.dll
celestia 1.6.2 needs lua51.dll
celestia 1.6.2 does not recognize lua5.1.dll even if it is renamed lua51.dll. The dll must have an internal name and it is the one that is verified by celestia.
When I use celestia EP V3, I got into the habit of launching it through Decoda (lua debugger). This made it easy for me to find bugs in LUT5 modules when I was working with our friend Croc. And I continue to do so.
As Decoda does not know how to work with 64-bit programs, I launched celestia 1.6.2 without Decoda. I did the same with celestia 1.6.1.
Observation: all versions of celestia with LUT5 and without Decoda do not display the elevators.
It seems that there is a bug in LUT5 but that Decoda does not report. In fact Decoda seems to act in protected mode on lua scripts, correcting certain errors. It will be very intelligent but will oblige to always work with Decoda which is not possible with celestia 1.6.2 64 bits.
Croc, to whom I had offered my modified version of the Vidiba module (with its window lift), encountered no error while working without Decoda.