Brake fluid reservoir leak?

I have a flying RV6A with dual brakes, which I did not build, the plastic fitting on the brake line at the reservoir inside the cockpit appears to be leaking, the fitting on the line appears to be tight. The reservoir is on the firewall in the engine compartment. I cannot find a drawing for the reservoir on the firewall to the brake- line assembly.
Any suggestions on how to trouble shoot the leak?
Jim Skinner
Exempt but gladly donate.
RV6A flying
RV6 regrettably sold

DWG 36

There are details in DWG 36 (page 58 of 76) in the RV-6 Plans - ALL pdf if you bought the pdf plans on a flash drive.
Mine leaked too.. I drained the brakes.. had a helper help me remove the reservoir and nylon tee. I cleaned up the tee fitting, put a little bit of sealant on the threads of the tee going into the reservoir and put it back together and no more leaking.