[50mhz] Yaesu FT-690 RII part?

[Bill Aycock]

Greetings- I have just acquired an FT-690 RII that appears to work 
fine except for the Lamp.  The users manual shows a screw in the Amp 
body that pushes a switch to turn the lamp "on"; the instruction to 
turn the lamp "off" is to remove the screw.
In my radio, the screw is missing. ( Apparently a past owner took it 
out and either tossed it or lost it.)
Does anyone know the description of this screw?  The head size and 
type, the thread count and size, and the length would help mightily. 
Anyone furnishing clues about this will earn my gratitude.
Thanks- Bill-W4BSG