OK, so in continuing.  I have added new (oe) H/G oil filters & using the dual barb fitting added fluid.  I could only get
all but 16 ounces in of a gallon on 2 internal expansion 2800 units.  Let it sit 2 days.  Checked fluid level & it was to level.
Then with dump valves released, started it, rear off the ground & at low rpms run the sticks slowly 6 times times.    Stopped it, leveled it on blocks & then checked fluid levels,  they both wanted more fluid in each.
Now I am about 10 oz short of 1 gal total.  & will have more purging to keep doing maybe tomorrow.
Any advice would be greatly appreciated..  These are my 1st serviceable hydros.