Hi Both,
Thanks for the reply both, i will try to reply factually to the questions :)
Firstly the Scale is 00, and I don't believe there are any known current hogs, but there is one loco with a stay-alive (the rest do not have this) - i will test with the multimeter.
1. I have the 15v 3.3A power supply bought with the sprog 3 at the time
2. Its running in command station mode on JMRI, and in Ops mode for the rolling road for programming, where there is no issue at all with the locomotives that 'stop' on the main layout
3. The Bus Wiring is 30/0.25 with 16/0.2 dropper wires every 2 lengths of Flexi Track (these are soldered together, so the droppers are soldered under the joint) You may observe the wiring is a little beefy, but its also needed to carry the AC current from the Hornby Live steam that is interchangeably powering the track (there is an isolated engine shed area that cannot be fed when the live steam is running so no harm can come to the normal locos)
4. It seems to be a sporadic occurrence with different locos but never at the extreme other side of the layout
5. It doesn't seem to matter on the quantity of locos, or if they are all sound fitted and running or not, there are usually two running, and another 6 on shed, but only 3 of the locos are sound fitted and when not in use are 'off' as it were
6. The sprog lights seem to behave normally.
7. I will put a multimeter in series and see what happens and report back (i am away until saturday so it will be at the weekend)
8. The only other thing i have noticed yesterday evening is in the JMRI window (running on Ubuntu) there is a constant Warning message for the delay time to communicate with the Sprog 3. this is slightly strange as the device is connected with less that .5m of USB cable direct to the laptop, running JMRI 5.2 and the latest install of Java.
I would like to add, that I am delighted with the Sprog 3 as a product, this has been my only issue since having it on the layout this year (since Christmas) and why I am trying to (hopefully) prove its not at fault, its just strange the issue is removed when only using the Gaugemaster - hence the question for the USB interface as i was trying to narrow the issue down to the JMRI sever, or the base station.
Thank you for all the advice and questions!
Rob