Hi,
actually, the advice to white-glue the N-Scale Rapido couplers together seems sensible when you notice, that a quarter of them is not straight (tilt sideways and upwards). But then, I want to couple and uncouple and with the questionable cars, there is no easy way to exchange the couplers (cheapo-moulded plastic parts). Exchanging them for Kadee-N-Couplers is problematic, since they are very uncommon here... I was thinking about a modified form of wire-and-hook couplers, but the work involved seems rather tedious (and I still haven't finished the trackwork...).
So for me, short pieces of wire to hold the couplers together will be the solution for now, but I will continue to look into alternatives ;-)
Oh, actually, at least here in middle Europe, Hook-Couplers are still the "standard" in HO. You won't find Knuckle couplers on any factory-sale models. You'll even find it difficult to buy them at a shop...
Have fun...