[Kenwood] TM 733a

[GGLL]

    Hello, I'm having trouble with a Kenwood TM 733A dual bander; front 
panel buttons and band change pushbuttons do not work, except that of 
PWR. The only way I have to change frequency is from the hand mic 
buttons (anyway, "MR" works strange because as first depressed it 
changes the op. band and thereafter changes to memory mode); all othe 
mic buttons work fine. It seems as a panel button being stick on, but a 
cold measurement shows nothing wrong with any of them.
    Reset, with PWR on and "MR" does not work also, changes to memory 
scan only. The same happens pressing "VFO" button, it changes to VFO 
mode and then begins scanning. It seems to me, until a steady state 
during power on is reached, that button works as intended. May be a 
built in circuit reset problem?.
Thanks for any hint.

Best regards
Guillermo - LU8EYW.