Hi guys!!!

I have a leak between my master cylinder reservoir and the cylinder body. There is an -0- ring connecting the 2, a only takes a little wiggle to see fluid leaking here. Looks like there's on screw on the cylinder holding the reservoir on.

Anyone tried repairing this... hints or suggestions, or knows size of that -0- ring?

And... if i can't match it, what do you think about disassembling and sealing the existing -0- ring with RV silicone?