Code:
Transmit:
@ INT_DISABLE   INT_INT     ; Disable external ints to stop Echo RX
INT_INT is the same as INT0_INT.
But you are using INT2.

In the BlankGain: handler, you have ...
Code:
              CASE IS > 14
                GOTO EndGain                '
That will use PBP's system variables. Which means the handler can not be an ASM type anymore.

A CASE ELSE might fix that problem.

There may be other issues, but that's a start.