Our slat slots are pretty well munched. The previous "crimper" didn't so much roll the gap shut as squish the hell out of it with vise grips...after installing the awning cloth upside down.
When we ordered the awning cloth, we ordered some 4' lengths of something we could rivet on that edge as a replacement channel, if necessary. We'll have to balance the re-forming results against the rivets we would need to attach the new channel.
I think we might have some 1/4" steel rod kicking around that could do the same job as the drill bit as the "anvil."