I think you have to be careful about cleaning your toaster, getting out the crumbs in the tray or any that have gotten stuck in the works. As they get older, they do seem to get too hot on the higher settings, so you might want to try lowering the setting.
I’m still very happy with my 10-year-old Oster, but we do notice that now, the setting we’ve always used burns the toast; so we have lowered it. I don’t know the reason for this, but perhaps some electrically-minded person might inform us...
As I recall, “toaster shakin’s” were a delicacy in the Bundy household.