I digged some old and still nice speakers from my basement, but on one of the speakers the central portion of the cone technicaly known as a ‘dust cover’ was pressed towards inside, so I thought of some kind of vacuum to pull it back. It’s not perfect since its old cone and it certanly does not affect the sound quality, but its a great idea anyway worth sharing.
Note: pictured above is Ratho-Hamburg RTO WR-200P model (polypropylene-cone membrane) and in my video is ordinary WR-200 (paper-cone model).
My vacuum cleaner isn’t so strong so it was a longer task, ideally the stronger = the better (800-1200 watts) so you can pull it with one or two trials.
PS. Sorry about the sound, forgot to turn recording mic.