courage, you made my day today, it is indeed the usage of Variants that was required in this case, still a little bit difficult for me to understand but at least I can make it work and move on now. Thanks a lot and thanks to jdporter for having faith in me, he gave me the courage to keep looking, and it did not take six months. :-). Just for the record the piece of code.

for my $placement ( in $Recipe->Placements)
{
            my $PartNum = Variant(VT_VARIANT|VT_BYREF, ""); 
            $Library->FindPart($placement->PlacementPart->Part->Name, 
+$PartNum);
            my $FeederType = Value{$PartNum}->MachineValue("FEEDERWIDT
+H") ;
}
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