[Yaesu] FT-900 question

[Floyd Sense]

I had to put my FT-900 into service in the main station the other day, and
have noticed a problem.  I don't have the service manual at this time, so
could use any ideas you may have.

When using the FT-900 on CW, driving my AL-800H amplifier, the FT-900 drives
it to full output with about 60 watts out.  However, I noticed that the
output power from the FT-900 rises slowly when the rig is first keyed.  With
the VOX switch in, and NOT operating full break-in, and the keyer set for
around 20 WPM, if you send a string of dits, the output with the first dit
is very low and does not rise to 60 watts until the fourth dit in a row.
The FT-900 autotuner is set on and is properly adjusted so the 900 is seeing
a very low SWR on the linear input (<1.1:1)

If I depress the MOX button, the first dit is at full output as it should
be.  Likewise, if I press the VFO Split button, the first dit is at full
output whether or not the MOX button is pressed.  Turning off the tuner on
the FT-900 makes no difference.  The situation occurs whether or not the ALC
line from the amp is connected.  If the ALC line is connected, the ALC
operates correctly in controlling the FT-900 output, but the observed
condition is still there regardless of the ALC setting.

Any suggestions?

K8AC