Leaking Lippert Slide pump - with pics

I want to thank everyone here for the information! My father's 5th wheel uses this same system and it has been leaking out of control for some time. The actual pump says Controlled Movement Systems CMS0007, and the plastic reservoir says Haldex - Barnes Hydraulics. I determined that it was a bad o-ring installed between the reservoir and the motor. Using advise here, I purchased a #348 quad-ring and a 4.5" hose clamp. I installed the new o-ring and tightened the clamp against the flange as best I could (the o-ring sits a little further forward but the clamp can't hurt) and so far we don't have any leaks. I highly recommend the quad-ring, it has a much better sealing surface that a traditional o-ring.

I work aircraft hydraulic systems in the Air Force, but the simplicity of this system confounded me for some time before I visited this forum. Thanks all!