On Thursday, August 8, 2019 at 7:28:30 PM UTC-7, Tony wrote:
Richard,

The failures to start that I'm familiar with are all JS-1's

It was discovered that the M+D jets were being delivered within tolerances, but reliability could be improved by using more finely gratuated feeler guages.
Essentially: The tolerances were too wide. Keep the alignment as close to the specification as possible to achieve a more reliable start.
Jim