These are very poorly made circuit breakers. I bought one and right out of the box it was clear that it was defective. The switch would not snap positively in either direction. After confirming that the meter was defective, I sent it back and ordered another one, thinking it might be a one-off item. The second showed up and had the same problem. I sent it back and ended up ordering a used one elsewhere. He worked correctly. Having not made original Zinsco switches in years it can be difficult to find a good used replacement but I wouldn't trust these cheap Chinese knock offs.
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