If they're new enough to be under warranty, take them back. If not and you can open the speaker, I'd just splice and solder a suitable length of speaker wire right to the internal wiring. The fewer mechancal connections, the better.
I have Altec lansing acs33 speakers and the sometimes one speaker doesnt work but if i move the speaker input wire then it works again for a minute or two but then it messes up again. How can I fix it?