For any of you DIYers out there, here is more information:
One of the main problems with the swing lever is placement of the swing to minimize friction on the plunger as it slides during pressing. I have done a lot of testing and here are my findings. One way to test for friction is to insert a strip (about 1/2 inch wide ) of paper on each side of the plunger, then put some weight on the lever arm and see if the piece of paper will pull out without tearing.
It seems that there is a "best" placement for each MA ( mechanical advantage ) used, so for MA = 5 to 12 the placement is a compromise, but the position shown makes the press work smoothly at all those MA's.