If you happen to have a 99,99% torrent download stuck in Transmission and you'd love to have a "recheck hash"; option, simply do this:

  1. pause the torrent download
  2. go to the terminal and "touch"; the file/directory (as in "touch mydownload.rar";)
  3. resume the download
  4. voilá, there's your hashcheck
Transmission Hashcheck