If the cam is fixed to the back of the cannon pinion then at this point I don’t know how putting the dial/moon dial on could change anything. It’s possible but I can’t think of any reason that it would.
We’ll cover the chime stopping problem in a minute but first the early chime issue.
Not having a clock in front of me places me in a position of having to ask some very basic questions that may seem dumb but since they can be common faults (things I’ve done many times) they are important to check.
Here goes the first one. Is it possible that you put the hand on upside down or that it was upside down when you had it running without the dial? Some hands are fairly flat and look the same from both sides. Could just need to be flipped over. I have a school house clock hanging right in front of me with a hand that is flat and looks the same from both sides. Doesn’t matter if I turn it over though as it’s a time only clock but if it did have a strike it would show a different strike time by a few minutes. If not then you can always correct the hand position by moving it on the hand collet as discussed earlier.
There can be many reasons for the chime failing to start. Of course the first thing to check is that the heavy weight is on the chime side. Also check that the hammers haven’t jammed in some way and that no hammer is being lifted after a chime sequence is over… this one is real important…the train needs to have a running start before taking on the burden of lifting the hammers.
Did it get through all of the chime points and then fail at the hour?