I have been silent for some time since: after an exchange of opinions on the Forum way back in February concerning dead spots, in the light of the comments made and of the fact that these comments allowed me to identify the cause of one such dead spot, I came to the conclusion that my layout had very many more potential candidates for producing dead spots. It was originally designed and built for analogue DC operation and had been converted to dcc by adding some droppers, but retaining the power clips. So, I took the drastic decision to rip up the whole track and relay it with droppers all round, in spite of having said on the Forum that I was not all enthusiastic about this. However, since the layout has nigh on one hundred individual pieces of track, including a good number of short straights, I felt that connecting two hundred droppers would be an enormous task and so in places I have connected two or three pieces of track together with bridges across the joint or soldered a dropper across the joint (probably highly unorthodox and not at all to be recommended). At the same time, I removed all the felt track underlay and replaced it with cork (hand cut from larger slabs).
After several weeks of intensive work, yesterday I fixed the last pieces of track in place and to-day I finished getting all the droppers through to the underside of the baseboard, not without problems where the overhead track sections are concerned. My ramps are sustained on columns and some droppers had to be led to a column to run down the side hidden in a plastic straw.
I then plugged two pairs of droppers into my dcc controller and got out the power car of my Class 156 DMU and saw that the dcc signal was getting through, but the main purpose of this test was to discover possible faults on the track. Running forward the DMU went reasonably well, but when put into reverse there were problems with derailing at a particular spot. I shall get out my DC controller for track testing, before I upturn the board to attend to the underside wiring.
The next immediate job is to refit 11 surface mounted point motors, but I have to suspend operations for a few days because my wife wants the garage tidied up.