Using a small file or a scalpel carefully remove a tiny amount of plastic from this edge at the bottom of the coupling a little at a time until a pair of couplings will pass easily through each other with a minimum of side play.
Too much rotational side play will cause carriages to lock up and derail when pushed through reverse curves.
File the bottom of the coupler shoulder flush with the tang.
Clean off any flash from the resin drawbar with a blunt blade or your finger nail.
Then set the buckeye so the bottom of the coupler is flush with the bottom of the drawbar coupling pocket. Fix with a small amount of super glue.
The Buckeye Coupler.
The real thing
As Bachmann do it.
Close coupled with Keen Systems replacement draw bars but without floating End Plates
Fitting the Drawbar
Remove the bogie by removing the securing screw. Remove the existing drawbar but retain the centring spring.
Fit the new drawbar into place and attach the centring spring. Refit the bogie and securing screw.
Remove the existing corridor connections.
Push the door in and cut the webs from the slots at the sides of the corridor opening.
Assemble the corridor connection. Ensure the end plate extends evenly about 1mm by adjusting the attitude of the fixing washer.
Fix the assembled corridor connection into the carriage.
The finished job
Carve or file the curved bottom of the corridor opening flat.
File the top of the end plate round to match the corridor connection.
MkII a,b & f Corridor Connection
The Keen Systems Buckeye coupler.
Used for permanent coupling between close coupled carriages.
Bachmann E-Z Mate MkII auto coupler.
The coupler is pushed well back in the coupling pocket. Good for coupling to locos.
A 0.5mm packing of plasticard is glued behind the shoulder of the coupler.
Use these couplers between the carriages and to couple to the loco.