I know this thread is kind of old, but I've been working through my SLS system. The valve rebuild kit Andrew sells is great. Easy job, just be patient with all the fastners and removing old o-rings as the valve body is aluminum.
As for leaks in the front, fluid was leaking THROUGH the hose between the reservoir and the pump. Replaced it with clear hardware store hose and it's been fine since. Was a little snug going on (I assume it wanted metric hose) but a cigarette lighter did the trick. Also, much easier to do that when you're changing the belts because you can move the PS pump out of the way to get the hose on the bottom of the SLS pump. Clear hose is a great way to monitor the condition of the fluid. My reservoir is pretty dark so I thought I might need a pump rebuild, but the fluid is clear. PO may have taken care of that, as I've read here that it only takes a tiny amount of fluid to make all the fluid black.
All in all, this is one of the simpler systems on the car. Not too many parts and easy to trace the lines if you can get under the car.

Glad your o-ring install went well. The SLS fluid get pretty dark over time, so you may have just had old fluid. Keep an eye the pressure hose coming off the pump. It's the one with the crimped ends. If it blows it will spray your fluid all over the engine bay.

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