Bleeding the brakes today and I had the same problem a couple other people on here had of one of the screws that hold the break fluid reservoir cover on not wanting to come out. Since the screws appear to made of a metal with a hardness akin to cheddar cheese, the Phillips head stripped of course.
In case this happens to you, the replacement screw size you need is a metric one. The size is M4 -.70 x 12. I found some at Lowe's.