The Dingham instructions recommend fitting the couplers to vehicles by gluing or soldering  because the spring and split pin method of attachment gives less positive location of the coupler. Nevertheless, several Dingham customers seem to want to use the spring and split pin system and asked me if I could help them find suitable springs. Potential suppliers seem reluctant to offer the relatively small numbers that Dingham customers are likely to want.

I now stock springs suitable for fitting the 7mm couplers in packs of a dozen.

Note that the pack includes only the springs and not the split pins. This is because the springs are difficult to obtain, but split pins can be had from most good hardware suppliers or a suitable substitute can be made from wire.

When attaching couplers by the spring and split pin method, it is strongly recommended that you remove the moulded or cast coupler pocket already present on the buffer beam and substitute an etched pocket from the Dingham fret. This will give a more positive location of the coupler because of its snug fit in the etched pocket.

At present, I am not planning to stock springs suitable for fitting the 4mm couplers because the spring and split pin method of fitting appears to be less popular in the smaller scale.