[Yaesu] FT1000MP Field Diode D1056

[Gus Samuelson]

De Gus  VO1MP

Am looking for some information  as to the possible root cause of this problem   
  I have a  pair FT1000MP  Fields and have had to replace  diode D1056 ( 1sv271 tph3 diode) 
twice before and now it  has  just popped again

  This diode is in the rx chain just before the band pass filters. It is a  chip 
component and difficult to solder but with care it's do- able in 
about 45 minutes start to finish, by my friend who is very adept at trouble shooting and
 with  soldering tools

I had always attributed the fault to the fact that  quite often I run two rigs simultaneously
and some how  got  careless .
However recently this diode  popped again , using it alone woithno other rig running,so 
 the  only common factor I can attribute to the fault is that each time it occured .
it  has been while the rig is  driving my alpha 78  ...  it has never  occured while driving my alpha 87a    ..

Some how now I think this must be related to the combination of  FIELD and Alpha 78 ..
wonder if anybody has  had a similar issue and  can provide a comment or  two about cause of this fault.
I had been keying the  amp directly from the Mark V Field  but   I have an amp keyer  here that I have  used with 
an sb220  that I can use  and according  to specs  the
keying volatge shud not be an issue  but one never knows ?
APPRECIATE ANY HELP ?