Often when I try to play a CD on my BS 4000 I hear a clicking sound and the CD doesn't spin.  If I press CD again it seems to work okay.  It makes the same clicking sound when I stop the CD - e.g. by pressing Radio.  It also makes the noise if I press CD when there is no CD loaded.  But after a while of playing the CD, it will operate normally.  It's my understanding that there are no belts in the CD player, so what is slipping?  Is the CD motor going bad?