[Yaesu] FT-757GX difficulties

[Jack/NA7RF]

I've encountered a few problems with my recently purchased '757, some of
which I can repair but a couple have me stumped:

1) No carrier null on USB but the receiver seems to be working okay. LSB
is perfectly okay. I have looked at on-line resources and see no mention
of this issue.

2) Inconsistent tuning rate. At some places in the knob rotation I get
normal (10Hz?) steps but at other spots the step rate is at least 100Hz.
That made tuning tough in the NAQP RTTY contest! Is there a possible fix
for this or can the encoder assembly be replaced?

Any suggestions would be appreciated.

73,

Jack, NA7RF