At least TWO reasons why exchanging the tweet is tricky (but hardly inpossible): mechanical & electrical
Mechanical: does the new tweet fit, are the mechanical properties similar b/ween the two tweets?
Electrical: (more tricky) the Thiele-Small parametres must be very close (if not identical) -- otherwise you're changing the original design of your speakers / OR you'll have to change the cross-over to match the new tweet's characteristics (i.e. you're changing the original speaker design)...
Mechanical: does the new tweet fit, are the mechanical properties similar b/ween the two tweets?
Electrical: (more tricky) the Thiele-Small parametres must be very close (if not identical) -- otherwise you're changing the original design of your speakers / OR you'll have to change the cross-over to match the new tweet's characteristics (i.e. you're changing the original speaker design)...