The 8th edition of the Repair Guide was the last edition to be strictly a "Repair Guide". Having offered a leatherback limited edition he was obviously pleased with it. When the 9th edition went to press in 1984 the 8th had been in print for six years.
The 9th edition was more than a repair guide. See the new sections included.
400-Day clocks were going to be around for a long time and perhaps he knew his book would needed for just as long; so he decided to put as much information as he had into a book that in some form or other might be in print forever.