I haven't seen that type of regulator, as I have a '51 with the single arm style. But I'll bet it uses a semi-tubular shoulder rivet at that pivot point. I've been able to buy those from Hanson Rivet in LA, but last time I called, they told me they wouldn't sell to me directly and I had to go thru Grainger to get their products. I used similar rivets to repair the pivots for the center cowl vent, and they worked well. Here's a link to Hanson's shoulder rivet page.
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