Thanks! Yes, this is a Klann knockoff. That makes sense - the annoying part is that when I put the tool in the first time I didn't compress enough coils and the spring wouldn't come free from the perches. After the faff involved in repositioning the tool, looks like I overcooked it on the second attempt.

I also didn't compress completely the first time around. The tool I have contains instructions which warn against compressing to the point where the coils come in contact with each other. I hate having to put a used part back in a car but in this case I suppose that's the only way.

Thanks so much for the help!
Adam