electric seat runners..

Some may have seen that i have a problem with the drivers seat on the wifes d2. What the problem seems to be the outside seat runner is loose at the back. If you wobble the back of the seat, you can see up and down movement in the rear part of the runner. I cant see any other posts on this problem and cant see anything in RAVE about this. Anybody have any ideas what could be causing this?

Simon