[1000mp] Fault - Help

[John MacLean MM0CCC]

Excuse the bandwidth if this has been covered before.  Only just subscribed
to reflector.

Twice in the last month (with little use in between) my MP has decided to
tune itself up in frequency, as if I were holding the UP button on the mic.
Both times this happened whilst in RX and there is no noticeable
consistency - instance 1 I was on 20m, and had mic, CW Key (and NA LPT1
keying), Rig Control all connected - instance 2 I only had the antenna
connected.  Both times nothing could be done to stop the rig tuning itself.
Even switching off and back on, the MP would just tune up when power was put
back on.  On the second occurance, on pressing AM, the MP stopped tuning
upwards, but was this just coincidence ???

Rig is 1996 model FT1000MP.

Any help/hints/suggestions welcomed.

73
John, MM0CCC.