Make a flat on a 0.8 mm thick, ø 8 × 3.4 mm washer, with a file or a diamond disk.
At the end #1, place this washer on the pivot, the flat allowing the washer to position itself behind pins that limit the rotation of the bogie. Optionally soften the pivot clips; this will facilitate their possible future disassembly.
Preferably remove the drawbars (a thing I did not do on the pictures below!)
Deepen the bogie pivot holes from the top: ø 5, depth 1 to 1.5 mm, to compensate for the lift (1).
Bend the end clips inwards — without breaking them — otherwise they do not play their role, which is to hang and hold the interior fittings (2).
Glue two 3 mm long pieces of 1 mm square Evergreen strip onto the bogie supports, side of end #2; round them slightly at the ends (3).
Prepare two wire guides consisting of two legs in 1 × 2 mm rectangular Evergreen strip and a “bridge” in 0.5 mm thick Evergreen sheet, as shown opposite. The dimensions are not imperative, but the length must not exceed 29 mm. Glue these wire guides under the chassis with liquid model glue, close to the drawbars (4). In the photo, these guides are not ideally placed. It is better to put them closer to the drawbar (rectangle in dotted lines). Their role will be to maintain the coupling’s wires while leaving them some clearance.