I don't think a few minor dings and dents really make a tin hat unsafe. If we had to throw them away every time they got a little scratched or scarred we'd be putting on a new hat every other day.
I got this one new in '84 and it has a lot of life left in it yet. No point in throwing something away just because it's not pretty any more. It still does the job.
Matter of fact it took a pretty good shot at Calistoga last year and all it did was tear the suspension a little. I think a plastic hat would have shattered.