WM Recorder 12.4 doesn't have problems making Windows Media files seekable. But if you need to repair Windows Media files and make them seekable, you can do it with WM Recorder anyway.

How to reprocess Windows Media .ASF, .WMV, .WMA files with WM Recorder:

1. Open WM Recorder and record a Windows Media stream
2. After recording hit the "View" button.
3. Select "Menu" -> "Saved recordings" -> "Windows Media"
4. Right click on the Windows Media file that you want to be splitted.
5. Select "Reprocess file"