If you have an old faithful wagon, coach or locomotive that can no longer enjoy a trip around your layout due to a missing tension-lock coupling, you may be wanting to attach a replacement so it can rattle down the rails once more, but where do you start?
If your model is fairly modern, check if it is fitted with a NEM pocket, if so, replacement couplings are easily obtained with a quick trip to your local model shop, but what if there is no pocket, or it is an older coupling that's missing?
In this instance, you will be starting from scratch much like a modeller building a kit, but don't worry, replacement tension-lock couplings are available in many different types (including older types) from manufacturers such as Bachmann and Hornby.
Once you have sourced an appropriate replacement coupling, you will need some way of attaching it to your model. This is the tricky bit as without seeing the model in question it would be difficult to advise, it may be that your replacement coupling can be attached straight to your model's original moulding or chassis, in which case you're only a spot of glue or a few fine screws away from success, but if there is absolutely nothing but thin air to attach your coupling to, you will need something called a 'mounting block' or 'coupling block'.
These blocks consist of a piece of moulded plastic designed to bridge the gap between your rolling stock's underframe and the height at which your couplings should be sited. The blocks come in different types to accommodate different couplings so you may need to ask which is compatible with your type of coupling, and even then, as all models are different you should be prepared for a little fettling or fine adjustment to get your coupling's height correct.
Although this all sounds rather complicated, in essence, it is just sticking a piece of plastic to your model and sticking a replacement coupling to that, so try not to be put off. What is important though is that you take a little time to ensure your coupling's height matches that of other rolling stock in your collection, failure to do this may result in unreliable coupling or derailments.