Re: I can't get the sensor to fit
"Clearly the Russians have a systematic quality assurance problem, and those ain't cheap"
Before this latest problem, the last time a Soyuz launcher needed to use its escape system was 1983.
A 35 year run of manned launch successes implies that the problem which occurred isn't systematic.
Clearly, there is some sort of quality management problem which needs to be dealt with. But given the long-term reliability of the Soyuz system, whatever the problem is, it isn't deeply embedded into the engineering or operational culture so isn't likely to be particularly difficult or expensive to deal with.
I do wonder about this point:
"As of September 2017, the two final Soyuz-FG rockets had been scheduled to fly in April and September 2020. However the Roskosmos leadership was pressing the industry to retire the FG variant as early as 2019 to cut costs and avoid problems with Russian security services, which put serious obstacles in obtaining avionics and associated technical assistance from Ukraine's Kommunar plant. As a result, at least one of previously planned launches of Soyuz-FG in 2020 could be performed in 2019, industry sources said."
- one might speculate that - just maybe - management has perhaps been pushing workers to get things done faster than usual, which could have contributed to the problem in this case. I don't suppose we'll find out about that one way or another.