[Yaesu] FT1000D XMT Problem

[R March]

My old faithful FT 1000D has developed a XMT intermittent.  The power drops
from normal to 1 watt.  This happens very quickly, on and off, sounding much
like a bad connection.  It has hard to induce (in fact it seams to occur
only with rare DX, hi), but is somewhat sensitive to mechanical vibration.
No problem on RX.  Has anyone else experienced a similar problem and found a
fix?  My first thought was relays, but outside of the LPF relays, their
really aren't any in the signal path, at least that I could find (?). This
happens on both SSB and CW.  Any ideas are welcome.(Relays, pots,
connectors, grounds, ??)   But I am especially looking for any known
failures that produce these results. Thanks,  Bob