Wharfedale Laser 100 W floor standing speaker - slightly broken - sounds crackly !

Wharfedale 100 Laser floorstanding speaker from the 70s. Not sure what is wrong with it but when the volume is turned up the sound starts to distort. May be the tweaker but not sure. Could be fixable. Everything is as it was when originally bought. Main speaker is missing the dust cap. Rest of speaker is in great condition. Feel free to ask any questions. Selling only 1 speaker.