Hi Carl,
i remember that there were two different seatposts from Shannon back in the days. "Shannon MTB Light" and "Shannon Hardcore". There were different screws used on both and if yours is an "MTB Light" the best thing you can do is to get rid of the aluminium screws. They are not save.
I always wanted a Shannon post back then because it was an available and affordable alternative to a Ringlé Moby seat post. They came in red, blue, black and silver and you are right they are made in Germany. A quick Google research says they are still in business and there is a third seat post now made of carbon.
Cheers,
Adam