Master cylinder stripped screw.  

This is my 1991 XR250L. Front breaks have never worked and I made this video showing how I tried to avoid drilling out the stripped out screw, but ended up having to drill and tap it.
As always thank you to all the channels that have helped me.
@2vintage, @northernmx5973, @mxrevival,
@LUNDMX, @dirtbikechannel, @upallknight91, @dirtniron, @CameronNiemela, @mppowersports, @TepcoCycleRepair, @whatshappeningintheshop
@999lazer, @thetwostrokerebuilder1590,
@mattberger02, @dirtbiketv, @TNTMOTO, @KincadePavich, @EMFTony,