Here's the more important problem: My "wild *** guess" for the height of the lower strut bar end was not good, it required too much range-of motion from the 20" strut.
My two options are (1) to carefully reduce the angle of the countertop support "L", coming down from fixed "l" bar which is TM attached. Or (2) Switch to longer struts with larger rang of motion ,also cutting new holes to attach those higher along the lift bars.
With either of those choices, My current holes lift bar holes, diameter 7/16 and 1/4, will have to be be abandoned and sealed up. They are only correct for "full open" position with the current countertop support angle
and the current lift bar length. The 20" struts became fully compressed before I was able to push the shell all the way down.
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I could have also tried to to reduce the angle of drop in the "countertop support" bars (raising the lower ball end upwards, closer to the TM floor), but the changes would be complex to guess or "measure", and such a change would probably required two new hole cuts in through THICK THICK steel (5/8") on each side.
I have chosen the "longer struts" alternative, buying this pair instead:
https://www.amazon.com/gp/product/B0BBMCRZX5/. This pair is described as "30.9 inch, 90 lbs". Arana also has a 29" model at 85 lbs and a 28" model at 80 lbs, but the 28" version had a much later delivery date.slower delivery.
I successfully removed the lift bar assemblies shortly after the test. The not yet-cured "weaker" anti-vibration locktite which I used was not yet cured, and it gave way before well before I would have created any from excess torque on the the ball mount shank.