I am not familiar with this pistol. I'm sure you've googled it, not much there. My limited experience with older semi autos has taught me that if it isn't broke, don't try to fix it. A friend gave me a 1949 vintage High Standard Model HB that he had screwed up trying to disassemble. I sent it to an HS specialist who repaired it. So unless there's a really good reason you need the serial number, I'd leave it alone. I don't know the source of your information on the location of the number, but it seems odd it would be hidden by the slide. Lots of guns made in the same era as yours didn't have serial numbers anyway.
Someone will be along shortly with better information and will politely point out my mistaken assumptions.
Good luck. Looks like a neat old pistol.
