Remove ALL screws. They all have the same length, except the one which holds the speaker itself at last; that one is shorter. The speaker sits under the red part left in first picture

Three black rolls on three metal-axles could fall out, just put them back like you see it on the first picture.

My speaker is okay, like you see on picture 2... The wires are okay and the speakers looks good too. So I reassemble it and had to look at the electronics-board, that you see on the third picture. It is in the other wheel of Rolliraupe. Also, unscrew ALL screws. Then it opens easy.