Being an Atlas machine, the pulley is probably ZAMAK. Which I wouldn't trust further than the nearest trash can. There may well be hairline cracks internally that only show up when in the middle of an important project. There is NO reliable fixing of ZAMAK, period. Long experience speaking here. I've dealt with the stuff since childhood.
A long, long time ago, in a galaxy far, far away, no belay that. A long time ago, nearly 50 years, a friend and I were rebuilding a houseboat. He understood boat building, I understood structurial mechanics. Together we made a middlin' good boat builder. There was a type of plywood, surely marine grade, that had 9 plys for a 1/2 inch sheet. I don't know what it was called or where to get it, but it was available in 16 foot sheets at the time. The current sheet would be 12mm. And a short, 2 foot piece would be enough for both pulleys. Just use good glue, Elmer's won't cut it.
Making a "T" shaped flanged bushing with a wide flange to fasten to the plywood would serve the rest of your life. And maybe your children's as well. It would require careful construction, and good sealing. But would be easy to construct the "round" part with a stand and a belt sander. You could make it as a pattern and cast one from aluminium as well, if you were of that bent. But, from my perspective, the plywood would serve as well as a casting. Or use the casting with the wooden pattern as a fallback.
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