Chris,

 

 I spoke with a man named George at Matco yesterday and while he was as helpful as possible he was not involved with the design or manufacturing of the hydraulics we use. George confirmed what I had been told by someone at Matco before that the locknut torque should be around 90 inch/Lbs. When I assembled the rod and piston and torqued the nut I found the torque sufficient to wrap a once flat AN washer around the shoulder of the rod and produce a beautifully conical washer. The mystery of the conical washers was solved. While 90 inch/Lbs is a normal torque for a 5/16 nut it is obviously way too high for this application.( Paul Nafziger, if you're reading this my apologies for the bad info when I sent you the sealing washers.)

I reassembled the thing (with my last sealing washer-more on order just in case) using maybe 25-30 inch/Lbs and all looks good.

 Since the machined shoulder on the rod was a bit small I found the sealing washer was sitting on the threaded part of the shaft. This didn't bode well for a good seal. George suggested putting the sealing washer on the front of the piston. This required turning the piston around and swapping positions of the O-ring and nylon backup washer. So now the order of assembly is; Rod, AN washer, sealing washer, piston, a thin AN washer, Locknut. I used 5606 as the assembly lubricant but next time I'll try Vaseline.

 Gear trials begin today!                  Kai