Are you shure this is an old decoder? This looks more like a analog electronic direction changer.
Not too bad, as such, as the original build 10470 was an analog machine.
So my question: has this steamengine an original analog DC motor?
This relay type was drawing my attention.
Some people are selling it; € 15,- for a single relay, others just ask € 4,50.
It seems to be a very special move to dump that relay into your "kliko".