I feel like it is very unlikely it was Eweka if all the files were incomplete/corrupted? They very rarely are with that service. Stuff that is like 6 or 8 years old comes down fine from there quite frequently.
I will say that if the show you are looking for is by a large enough company, they may have hired a takedown service that will delete just enough files to cause the entire thing to be corrupt depending on the newsgroup provider. Mainstream usenet service providers get hit the worst. If it’s something you really want to see, you may only have a few hours to DL it before it is corrupted in that case.