Bad couplers

[SWARTWOUT]

I just received a Dash 8-40C replacement for an older model under the $20 warantee deal.  Neither one of the Rapido couplers work.  They will not engage any of my Rapido cars or other locomotives.  My first $20 replacement didn't run either.  This is my 2nd $20 replacement where the coupler didn't work.  BooHoo!  I give up.  Somebody has to check up on quality /  design.