I did the same thing on my 1950. The pin is delicate and to the best of my knowledge you need to replace it now. Those needles get coroded and stuck on tight, but then break easy. I recently started a thread about which company has better quality speedos because I am looking too. What I have found, atleast for the AD trucks, is that you can buy just the guts of the speedo and save a bunch of money using you old housing. Someone with a truck like yours can chime in.
For the 50 I have found the speedo guts for $110-150.
