end of the story: success!
today eventually was able to do something on the spoiler. the idea was to remove the whole assembly to study it with a magnifying lens. 20 nuts later, with my son checking everything carefully, he found an arm on 1 of the micro switches bent enough to not touch the contact. carefully he straightened it and we assembled the whole thing. (no idea who did this before i got the car. perhaps as they had this problem were trying to fix it. is the only thing that occurs to me). while doing this we added permatex to all the nuts and the edge of the spoiler where it sits on the hatch.
some of the nuts were covered with rust or a white stuff. seems that there was water leaking in, so this will prevent it to happen again. anyway, we went to the highway to test it and presto! the spoiler went up at about 110 kph ( 65 mph) and down at about 60 kph ( 36 mph).
i hope that, whoever suffers from this problem considers checking the micro switches, in case there is something wrong with them. it worked for me.
there is a thread where this is being discussed at large and they also found 1 of the micro switches the culprit: https://www.crossfireforum.org/forum...tuck-open.html
it will be 1 week from now that i will have this car for 1 year, but for several reasons i was unable to concentrate on this issue. am glad that eventually i did.