What screwdriver do I need to disassemble RB67 focusing screen?

[MCB18]

My smallest slotted screwdriver will not fit in the space. I don’t know exactly what I need to unscrew the brackets so that I can switch the fresnel lenses of 2 lenses. @Mamiya_Repair seems like something you might know, but anyone is welcome to help out.

 

[Alex Varas]

If I'm not wrong a JIS #00, at least is what I use when I opened it.

 

[MCB18]

Ok, I did manage to open it and exchange the lenses using a glasses screwdriver. And man, those screws are tiny!

One more question, there seems to be a smudge on the matte side of the focusing screen, and I would like to clean it, but I don’t want to damage the screen (which I’m imagining would be rather easy to if you aren’t careful. Any advice?

 

[Alex Varas]

If it’s real glass with the lens tissue is good to go, if it’s plastic just blow it, don’t touch it.