One thing to be aware of when doing this job is to make sure the speaker cone remains perfectly centred when its glued up. If not, the voice coil will rub on the magnet causing a rattling sound and eventually burn out the voicecoil. You can test this by very lightly pushing down on the centre of the dust cap. The speaker should move down and back up without any scraping. if you feel or hear scraping, make sure you are pressing straight down and evenly. If still scraping, then re-align the rubber surround on the edge of the cone before the glue sets.