Process of elimination John. From the info you have given I would say the wiring from the head unit to the speakers is ok. So the problem may lie with a broken/loose wire between the changer and the head unit
or a problem with the connector inside the head unit.
If you can get to both ends of the wiring from the changer to the head unit, use a multimeter to see if the wiring is ok. If the problem lies within the head unit you may need to open that up to get at it to re-solder etc.
I have two hi-line heads, one shows Tape Error with every tape I put in, so I replaced that with a spare I got from a member and on that one the buttons used for entering the address into satnav and the volume control, are very sticky and need cleaning.
On these units the bolts I need to remove are M2x6. Problem is some are countersunk into aluminium. They will not shift so I'm considering drilling them out. I went to the local shops looking for replacements but they are too small for them to stock.
Long story short I found the ones I need on a website called Modelfixings.co.uk.
Make a note of this website if you have trouble taking very tiny bolts out and need replacements.
