I have now removed the Sat Nav unit from my boot, taken out the DVD disc but now it will not accept the disc back in.
Strangely, there is no eject button. The slider (fascia) has no electrical parts or plastic pins at all that would initiate an ejection of the DVD so it is a complete mystery how you would ever swap DVD's in this device.
I will look for a replacement (p/n: 86841-50100) or get it repaired. If anyone happens to know if other Units will fit please let me know. A couple I have seen look the same but I cannot see the rear electrical connections.
As often happens, I wish I had just left it alone.