Dave..
I agree with you, that meters with screws through the chrome, does not appear to be the work of a repairman, as it looks to professional to have been done in the field.
Wether it was done at the factory level, or by pro rebuilders... is a question that remains unsolved..
But..I have seen these meters, with and without screws when I serviced these units in the 80's.
When I was sent out to replace meter glass.. I can tell you it was a real blessing to find one with screws, when it was 40 below.
Why all the Canadian meters that have been shown on OG, are only the ones that have the screws in them.. I don't know.. Another mystery..
Even since I've been collecting them, I haven't run into any that have no screws through the chrome..Another mystery.
But, I can tell you with absolute certainty, there was both kinds in Canada.