Disco 2 CD auto changer

Hi all, the cd changer has stopped 'checking' the discs it ejects the cassette ok & I've made sure all the discs are seated in their recesses. The display in the h/u just says 'no discs'. Has anyone had this problem & sorted it or is it a case of stripping it & see if there's anything obvious?
Thanks in advance.

Does the read head thing need cleaning?

Hi Stan, not sure but when I get the time I'll remove the unit & strip it down.
On another note I've been working on the FL today which also has a cd changer under the seat & it turns out the cassette unit is identical (I swapped it over but no change, hee hee) so if I can't repair the D2 one I'll put the FL one in it. The D2 has a Philips hi-line system & the FL has Harmon Kardon so just hoping the changers are the same.