In very old German watches, from the 16th century, there is a mechanism called the "stackfreed". It is also called by that name in German and indeed it is a German word. But how is it pronunced? There might be an ethymologic expanation of this odd word with its odd spelling, but I'll save that for later, as not to bias the opinions of pronunciation.
"Schtackfre:d" "Stackfre:d" "Stackfried" or Stackfried"
Maybe not in any of these ways? Even if you, most probably, have never heard the word, it would interest me to learn about your "feel" of the word and how it might or should be pronunciated