If you got a bad coupler contact Langmuir, they will ship you a new one.
On the advice of @Bigdaddy2166 I ordered some of these to replace mine when/if they break or fail.
Several people have used these in place of the aluminum ones to get a better grip.
If you search coupler or coupler slip you will find allot of discussion about this.
Congrats on the new table! Have fun!