DAB radio (Barnard's Green WR14)

Made by Pure, model D240, probably about 13 years old. Has an alarm, and all the settings and display are fine, but there is a faint rumbling bass-note even when not in use. I’m guessing that’s there is some component that has failed and that there might be a boffin at the repair cafe who might know but I haven’t gone down that route. But I would be very pleased if someone else would..