I have a 2005 Landmark. It has three slides, bedroom, kitchen, and living room slide. The living room slide will not retract. It is always the last one to retract. When it begins to retract its as if the motor won't engage. I can't find in the owners manual how to manually retract it. There is a pump in the basement at the front of the trailer. The hydraulic level is about half full when the two other slides are in. I read where it should be about half inch from the top when all the slides are retracted. It may be low. When it starts to retract the living room slide the hydraulic motor starts to make a skipping noise and the lights all go dim. How do you manually retract the slide and what may be causing this problem?