Zeiss humphrey system startup state 19

I believe "state 19" is a weak main illumination bulb. Not sure if it's the same on your 740, but that's what the problem was with our 750i. Even though the bulb appears to be working, they dim over time and won't pass the start up calibration checks. On ours, there is a round access panel on top of the unit to service this bulb. Just be careful removing the bulb and don't bump any of the clear optical wheels. Part # 2660021106082 (for 750i. not sure about 740) Call Zeiss to confirm. Realize this is an old post so info is for future readers.