I have done a test "rework" of one by heating it with hotair and flowing flux and solder at the base of the springy collar to attach to the shaft rigidly. Came out tidy and strong, but hot-air won't be a feasible way to fix 50 of them, too slow to heat up the mass, hardware store style heatgun and rack them up into a row on a strip of wood perhaps.
But in doing so I found another problem, some of the cross holes are not fully drilled, it's like they used a step drill or something, I don't know, but the hole is wider on one side than the other (not all of them, but some).
I've bought plenty (hundreds) of this style of banana plug from Ali in the past, all been good before. Just shows you never know quite what you are going to get.