I believe you can lift the bridge off of the mainspring arbor (remove balance first) and that the 3 tiny screws you are referring to are to secure the arbor cup which is the arbor bearing to the bridge. I’m not absolutely sure as I don’t have the same movement here with me to check but I do have some Elgin kw movements here that have the 2 screw arbor cup configuration. I just can’t remember if there is much of a difference under the bridge. With the movements that I have the click is under the dial. Removing the dial reveals a small plate with two screws holding it down. The click and click spring are under this plate. There’s a small hole in the plate where a tiny pin can be inserted to push the click back which with the aid of a let down key the mainspring power can be released. I also checked an 18s key wind Waltham movement which has 3 tiny screws for securing the arbor cup and it is almost identical to the Elgin set up only with a slightly different power let down setup. It too is located under the dial. I don’t remember if the click and click spring look different on your movement but they may still be located under the dial.
Please let us know what type of setup you find and I’ll check around here a bit more tomorrow morning to see if I have an older Model 1 laying around somewhere.
’till then Enjoy BYJWR1,