Originally Posted by antdavison

I used to assemble loudspeakers as a part time time when i was at university .... to repair this you will need some glue in a squeggy type bottle, and another squeegy bottle with some some strong solvent ... we used to use MEK or tolulene ... acetone would also probably work .. also you will need you make a gap filling spacer.

First run a dribble of solvent around the surround material, leave for 5 minutes or so and remove the surround cardboard/plastic and foam.

To ensure everything is free then do this ... if you think you can get away without doing the below step , you need to be very careful when you reglue the foam surround, as the inner part of the voice coil should not rub against the inner part of the magnet's pole piece

Run some solvent around the central dustcap and remove (a stick with some double sided or doubled over tape is useful here) .. Avoid excessive solvent as you dont want to deglue the coil from the cone . Once removed, you will see the inner part of the magnet's pole piece, there is gap between the central portion of the pole piece and the coil which must be maintained to stop the coil rubbing against the pole piece ... we used thin plastic glued to a stepped cylindrical piece of aluminium or brass (ie non-magnetic) which had the same diameter as the central portion of the pole piece, the step in the alumimium sets the position of the voice coil ... though just a thin piece of plastic sheet, cut & bent into a circle would probably do if you are careful .. but this does not by itself set the position of the voicecoil ... i would precisely determine this manually ,, if it is too low it will bottom out during extreme bass, crush the bottom of the coil former and rub against the pole piece, ... in this case, because the disk shaped dampener at the bottom of the coil assembly is already glued to the speaker frame, the coil will already be well positioned ... what you are trying to maintain here is that the inner part of the coil former is precisely parallel to the inner part of the magnet's pole piece, and the gap between them is even

reglue the surround foam and cardboard/plastic with the spacer in place... the cone needs to have free movement in both up & down directions when set (so maybe first just reglue the foam to the speaker cone, then temporarily clamp parts together, without the gap filling spacer and check the vertical freedom of movement before glueing the foam to the speaker frame) .. , reglue the surround cardboard (or plastic) test, then reglue the central dustcap ... doing all this on some sort of turntable is the easiest method .. be careful of the thin voice coil wires if they get exposed by the solvent as they are very fragile


good luck