I've re-foamed speakers only once, which were some old Tannoys (C8's I think?). At the time, my trick was to feed them like a 2-3Hz sine wave as I adjusted the centering of the cones (while the glue was still liquid), which gave me some guarantee that I'm more or less where I should be and that there is no coil contact. They worked for many years since. Thanks for the video, nice to see as always.