Raoul, here are a couple of stories about surveyor I heard in the early days when I worked at Hughes.

A teacher I had was an engineer at Hughes at the time. He told a story about
the early development of the spacecraft. They were performing a test prior to
their full scale drop test of the landing system. They attached it to a balloon
to lift it to 1000 ft and turn on the electronics and landing radar. They did
not intend to drop it this time so they didn't fuel it. At 1000 ft they turned
on the electronics and then turned on the landing radar. All of the sudden BOOM the
pyros that separate it from the balloon fired and it fell, crashing to the earth
destroying the test model.

In the subsequent investigation it was determined that there was a great deal of
electronic noise from the radar, which got into the electronics that fires the pyros.
They allowed as it was probably not a good idea to have armed the pyros since they did not
plan on dropping it on this test. But of course had they not, they would not have found
the noise problem until a later test, which could have been even more expensive.
After that they put a lot of filtering to keep the radar noise out of the rest of the electronics.

The other story was told at a discussion about the Surveyor 4 failure.
They lost all contact with it just prior to the retro engine shut down.
The team that studied the failure had gone through a painstaking look
at what would happen if the retro motor had exploded. They tried
to trace where the pieces of the motor and any other shrapnel would strike the
transmitter, or antennas and cables and cause such a sudden termination of
signal. They had noticed that all the data was there at one telemetry cycle,
and gone when the next would have come milliseconds later. It didn't stop in
the middle of a cycle. They could not find any scenario that would not show some
indication that something was going wrong before termination of signals. The only
conceivable one would be if the plug between the transmitter, and the antenna
had simply fallen out. Even that was not considered likely. It could be the
spacecraft landed perfectly and sat there waiting for commands from earth till it died.