Loose crank knob arm - Petzl Laser Speed Ice Screws

I have several very sharp screws that I pretty much avoid using because at some point I accidentally tried to crank too hard on them and now the crank knob arm basically falls open under it's own weight. 

Looking closely at the crank knob arm it looks like there is a deformed washer that keeps a certain amount of pressure on the crank knob arm, and this washer is now flattened out enough that the arm is more or less free to open. The arm is attached to the screw with a rivet. Short of drilling out the rivet, and replacing the deformed washer and rivet is there a way to fix this?

 If not, what shall I do with said screws? I hate to just toss them, but I'm unsure if others would want to purchase and use them. 

So the arm flops open on its own? So what? That's not a load-bearing part. As long as you can screw it in and out, keep using it. This isn't a safety issue (if I'm understanding it correctly)

Plan B - I'll buy 'em for CHEAP.

Perhaps it's all urban legend but I vaguely remember hearing that during a lead fall, a rope was damaged by an extended crank arm. So my hesitancy to use them is over that safety concern. Maybe it's a hypothetical concern instead of one which actually has happened. It does seem plausible at least. 

You could hit the rivet with a hammer and punch to tighten it back up. I've seen many of these loose arms.

Put the head of the rivet on a heavy hard surface. Put a blunted center punch into the divot and strike it with a hammer.