[Elecraft] K2 Relay problem

[graham knox]

Gents,
      I have a K2 Serial 5375 which has performed perfectly since
completion 5 months ago, unfortunately it has recently developed a fault
I need  some advice on. The fault which causes the rig to function on
160m 30m &15m only is intermittent.I have found when the fault is active
that K13 remains in the reset state, I can usually clear the fault by
making several band changes or cycling the power a few times which puts K13 in the proper state for the selected band.
I have checked all soldering around RF U1 & the relays to no avail. When I
removed the control board to reset the relays I found powering on did
not cycle the relays as per fault finding guide.I feel the problem is
probably U1 or k13 but would appreciate advice on isolating the fault further.
                                              
                                          Regards  Graham  G4cpd