Phew! I'm pleased to say I've managed to partially recover from the recent set backs described last time.
First, the replacement illuminated magnifying glass has arrived and is ready for use, so at least I'll be able to see the jobs in hand!
This morning I got out the mini drill with a rotary burr and ground away more of the inside of the Jubilee resin firebox such that it now fits over the motor whilst missing the whistle. Getting the front fixing screw in before the new lamp arrived was a tricky task but accomplished on about the tenth attempt.
On Saturday, I thought I had better check to see if my DCC control system was working at all by trying out one of my existing DCC locos on the test track before starting to rip bits apart. That worked OK, so I then tried the Jubilee chassis again, using the default address 03 and, lo and behold, it worked - rather spasmodic - but at least it moved, proving that the chip is not completely dead. I think the issue with the loco now is pick up related so I need to get the tender pick ups connected to the loco and see if that improves the running.
However, the failure to change address suggests that there is a problem with the programming aspect of my DCC power unit or the way I have it wired to the track. Further investigation is needed with possible replacement in the future.
Dave.