Circuit breaker problem

A mate of mine has a three phase supply in his works, one of the single phase breakers is getting slightly warm and tripping randomly. It's not a
DIN rail mount, the breakers have clips at each end, one on to a locating rail and the other to the busbar. Seems to be an obsolete design (there are a few on eBay but not the right rating). Anyone know of any possible suppliers? I'm not even sure of the correct name for them.
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If you can identify the type on fleabay by item number someone may be able to help.
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