Issue Uploaded STLs are not watertight #1
The STLs as uploaded by you some time ago are not watertight and may prove troublesome for some slicers. Would you be able to fix them?
I am very sorry to hear about your problem, but I cannot currently confirm what you have described.
In the 3D software SKETCHUP, which I prefer, all STL files are flawless solid bodies without gaps or holes, which is why I cannot repair anything that does not seem broken to me. Cura "v15.04.06" (32Bit), Cura "v4.3.0" (64Bit), and ChiTuBox "v1.6.1" work with no apparent problems with the STLs available for download on Thingiverse and Youmagine. You may have corrupted downloads, the import function of a 3D software may not work properly, or incorrect slicer settings may be the cause!