A while back also found some similar levels on ebay, and bought bought several of them. Placed them on a granite surface plate next to each other and one was no good, two not quite acceptable (used them on my pinhole camera), and the rest passed. I used JB WELD to attach them. Going on probably 2+ years and still working.
Don't use the superglue on it, as it can haze/craze the plastic, and harder to get off if needed...
Use contact cement...
Steve K
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