I have compiled both 32-bit and 64-bit DLLs from v1.7.2 sources found here.
Here's the download link for the binaries. I have minimally tested both 32- and 64-bit versions, and they at least produce the expected output from the tiny code sample that I fed them. My 64-bit version is smaller than the one currently found at our download site, possibly due to Release vs. Debug build.
Please, put both files in http://downloads.factorcode.org/dlls/.
Hard for you to know, but it links to the wrong C library "msvcr100.dll". It's a redistributable dll shipped with vs2010 and you're supposed to bundle it with the program you are shipping. So it is probably better if you recompile with vs2013 which will cause the dlls to link against "msvcr120.dll" which we already have other dlls that link to.
Even better is to link to "msvcrt.dll" which is shipped with Windows itself, so you don't need to add anything extra, but modern versions of VS doesn't let you do that.