[Elecraft] KPA500 ser. no.1066 factory built, Loose diode 1N5408

[Poul Erik Karlshøj (PKA)]

We have found a loose (de-soldered) diode 1N5408 in this factory assembled KPA500.
The diode shows >10Mohm in one direction and 2-3 Mohm (varying) in the other direction (DVM)
Where is this diode located (if there are several, then where?), what is its function and is it replaceable by a skilled tech person?
What could be the reason for the failure - it does not appear to have been over-heated, so desoldering appears not logical.

Is there a diagram of the KPA500 available?

73 from
Steen and Paul
OZ8SW (owner) and OZ4UN