I've been trying to find a solution to this problem and couldn't find any. I'm running Amarok 2.4.3 on OpenSUSE 11.4. I use slim toolbar view in Amarok. I notice that the seek button in the player's bar appears and disappears. When it appears, I can have the repeat track function. Otherwise, it doesn't work.

Does anyone have the same problem? Any solution to this?

Which Phonon-backend do you use? Seeking is problematic with the gstreamer backend and does not work on Streams and Flac files AFAIK. Try using the phonon-backend-vlc instead.
And of course, please upgrade to Amarok 2.5