Clutch master cylinder to fluid reservoir leak

Hi all
Some weeks ago I fitted a new original type brake/clutch fluid reservoir and new pipes from the reservoir to the master cylinders. The brake side remains dry however the connection at the clutch master cylinder to the clutch pipe leaks slightly. It is only a very slight leak but I cannot stop it however tight I tighten the fitting nut. I top up the fluid every 6 weeks so which I can live with but I am tempted to try fitting a yet another new pipe however I am not convinced this would solve the problem. Is it realistic to drop an o ring under the pipe and tighten onto that?
Would appreciate your advice
Thanks
Steve

You need to make sure that the flare on the pipe and fitting are not damaged or out of shape. a small amount of PTFE tape will seal it
Also check that it is not leaking out of the fitting on the bottom of the reservoir, they do leak from there but dowty washers work better than copper

Dowty washers (steel with viton centers) work great. I think you need a third one between the clutch reservoir insert and the floor of the main reservoir.

These function like an o-ring contained by a steel washer. They are 1/2" ID.

Thanks both
The leak is not under from under the reservoir but at the connection at the clutch master cylinder. I guess I should try PTFE tape first.
I had not heard of Dowty washers but can imagine they would solve many leak problems.
Steve, were you suggesting using one of these under the pipe flare? Is the bottom of the master cylinder threaded hole flat? The od of the washer would be about 9mm and the seating diameter of the flare on the viton seal would be about 5mm.
I wonder if you can get a Dowty seal this small. I will check.
Thanks for your help
Steve

Steve -
The Dowty washers are for the fittings on the tank. They won't work on the master cylinder.

You'll need a new supply pipe, which comes flared with tube nuts. See item 90 below:



If the flare on your new supply line is leaking, it was not made properly and you have grounds for getting a replacement.

Thanks Steve
Appreciate your help.
Yes, I'll get another supply pipe.
Cheers
Steve