But I am skeptical it would make a real difference given that there is not even a little catch on it.
For my use in the photo above the holdfasts were pressed into the dog holes with only hand pressure. They can hold fairly well for many tasks this way.
It should be possible to insert the shaft into the dog hole, hold the shaft at an angle and feel resistance or move the bench when it is pulled out.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)