Hi just to update you.
I decided not to go for the obvious and easy option (as often) of purchasing a replacement motor. Instead I hunted down a shop that is looking into the matter and claims to be able to solve the issue. The place itself is totally fallen out of this time, run by the father and his sun (not sure who is who :-), cramped with tools and items to repair, with no service orientation "We shall let you know when it is ready", the response to "When that could be?" was "Certainly this year, but we shall not promise anything" but a real interest in these "Old things" as the person very warm-heartedly said. So in a way cool :-)