Hello from Germany ! Today I bought my first Athearn RDC's. I tried to install Kd's but the coupler box slips over the screw. I find out that the centering spring will hold the box in position. But HOW can I fix this spring in a position between frame and coupler box ?? Must I have 12 fingers or must I say : "abracadabra" to this item ? I get crazy and put the RDC's in their boxes (for a short time I hope). And who has this amusing rubberband drive invented?. Or has this any advantages ? I hope someone can help me with those probems, Stefan