Driver seat mechanics problem up down discunction

Hello Leutz, the mechanics of the driver’s seat has given up the spirit, should mean that the up down mechanics no longer works, the lever does not seem to work properly. With a lot of feeling it works in some cases rather bad than right. Who has experience with this topic? New purchase always goes, but does not have to be, I like to try to repair it, alternatively to acquire a used one in case of failure. You understand? Is there a PDF of the inner life of the seat of the mechanics and what must when installing and repairing? Looking forward to answers, thanks. Greetings Holli PS: I made picture and video.