[sleightofhand]

I bought a cheapish 1/4 to 1/4 10ft extension cable from Guitar Center, the brand is Hosa, to pair with my Grado's 325is. 
But, when I move around while connected I lose sound from one channel or the other or all together. 
When I place the jack into the ext cable it wiggles without much coaxing. I tried other 1/4 jacks, which also felt loose in the ext cable, but less so.
When I place the Grado's directly into my headphone soundcard amp, it lacks any sign of wiggle and is solid. Which makes me believe the ext cable is the issue.
 
Do I have a bum ext cable or is the jack on my Grado improper?A mix of both?
Should ext cables provide solid, wiggle free connection? Does Hosa just suck, or should I try I different cable all together instead of exchanging it?
 
Should I get Grado's ext cable? Are these good quality and worth $40, which I believe is a fortune just for a cable?
Should I replace the Grado's 325is' cable? Is that even possible?
 
Side info: I purely use the cable to watch movies late at night, so as not to disturb others (upstairs).
When I want audiophile I plug in direct. So I just need a solid connection and less concerned audiophile. 
 
Thanks.