John Deere 410c

Old 410c backhoe when I first got it power steering was hard to turn as in no power assist raised front off the ground worked back forth till it loosened up . Not sure where it get its hydraulic power from ? Replaced lot of old hoses an cylinder packing have a new problem reversed is making fluid an seam to be losing hydraulic fluid .question what point on the backhoe do the come in close proximity together like separated by a gasket or seal . Question in the oil cooler can the two fluids mix ? I do pretty much all my own repairs but don't have a manual any help from someone that knows this machine would be greatly appreciated