I was partially responsible for somebody I know getting an Allora pocket trumpet. When I played it it seemed alright, but since then it has come back to me a few times for advice on moving the third valve slide. It's always sticking in some fashion - it comes out easily enough but is not easy to get back in, especially for a 10 year old. I've never had my own pocket trumpet so am unused to the technique in manipulating the third slide (see photo link for the style it is). I can only get it back in by rocking it gently up and down as I push (also gently). It takes a while and doesn't seem 'right'.
...or here (seems to be a common configuration)
Is this just a poor design choice? Does anybody have a good one? Or the right technique?