The 2.3 update is only to fix issues with eject problems on the D2C2 and D2C consoles. You'll need the D2Prog & flat cable to flash the firmware to the chip.
If you have a D2E system, then flashing the update will cause the chip not to be compatible with your D2E system.
Are you using a clip or wire install? If a wire, then you can ask your installer (if (s)he didn't already do so) to route the CLK wire over the D2Pro's oscilator, and add a wire for 1.5V. Sometimes that helps.
Best of luck