These ‘lenses’ are not just lenses but the complete optical module consisting of two lenses, two prisms and two sensors assembled and adjusted into a component.
See also:
This is a highly delicate optical design requiring special tools for assembly and adjustment during manufacturing. There is no chance to disassemble this module in order to ‘fix’ its parts such as a scratched outer lens element. Not even Ricoh can do this. If you need a fix, just replace the complete unit!
In addition, this optical module is probably the most expensive part of the complete camera. Getting it as a spare part will not reduce repair costs significantly. And when talking about using the module from broken cameras you should consider that most THETAs are broken due to a scratched lens. 
Good luck!