The solution to put a small piece of rubber between the split pin works like a charm!
I used a tiny flattened piece of small diameter shrunk heat shrink tube and it settled in there nicely.
I also built a "rack" to hold the V3 such that the rack it's attached is about 3" deeper; ie rack is about 9" long compared to the approx 6" depth of the v3 so that when resting vertically, there's no stress on the power cable or anything else in the back for that matter. Kind of difficult to describe, but it was made from 2 storage racks from Staples, a torch for bending metal, bolt cutters, snips, cables ties and, of course, shrink tubing.
With both improvements, the power plug will now remain securely attached.
/Ken