1950 Dodge Speedometer ?

All my experience is with much later examples.
I have a very long surgical clamp ( forget what its called, whisper roach clip ) I can slip behind the screen and lightly grasp the sleeve part of the needle. I rotate the drum like part of the speedo to move the needle half way around to get away from stops before attempting to work the needle off the stem with this tool rotating both clamp and drum as required to work the sleeve off the stem.
They do look like they could be pulled off with finger tips or pry against the screen to get off but... Many of them have a dollop of epoxy like substance hidden behind the center button opposite the needle that serves as counter balance. If that stuff should crack fall off, the speedo wont work right.
Good luck with it.