Almost certainly, as the pipe to the gauge is from the boiler and without the glass there will be no pressure in the boiler.
I suspect something else in the problem. The gauges I'm familiar with should work even if the glass is broken. Steam pressure gauges are typically based on a bourdon tube - a sealed curved tube that straightens as pressure increases. Through a linkage this turns the dial. Broken glass could stop the gauge working if it interferes with the mechanism but this alone won't stop the pressure building and the locomotive from working unless the tube has been broken.. Nevertheless you should replace the gauge....
Before broken, I saw some water precipitation in the gauge. Then, I decided to remove and clean it, but during the process, the glass was broken. The reason water precipitate in the glass is probably due to the overfilling of the boiler. Regardless of this broken pressure gauge, the locomotive never run even I observe strong pressure released from the safety valve. I am not sure if Accucraft tested the locomotive before sending it to me. I am in contact with them to return for service.
I also think similarly, but when I discussed that with Accucraft service people, they didn't say anything. They asked me to send back for fixing. I think I can replace the pressure gauge, thus it saves me a lot of time not sending the locomotive back there again.
To test this theory, I guess tonight I will remove the broken pressure gauge and put the screw alone back to the place, and now based on the design it is a closed system, I am certain to see the pressure will buildup, and it seems likely.
Interesting... since the pressure gauge is removed, is your way to "see the pressure will buildup" a popoff valve venting or just a boiler explosion?
