I got the driver out of my MSL3. It's 25 years old and I did replace the diaphragm a couple of years ago. It's blown again and my impression is that the ferrofluid dried out and caused the damage. The driver is a JBL 2450J-1
I've looked it up and it appears that I need to clean out the old fluid and put in a bit of fresh fluid.
Does anyone know where I can get a small quantity of speaker grade ferrofluid.
There are a good number of different "types" of ferrofluid.
I have done testing, and different ones produce different results.
it is not "one size fits all".
There is also the chemical consideration.
Some ferrofluids attack different glues used in the driver assembly. So you need to match the fluid with the glues used.
I have seen it attack dome materials as well.
I would hunt for the proper one, as used in the original. Otherwise you are taking a chance on performance or damage.