Gotta love this site for getting answers! Thanks for the additional info Phil.
Here is my master cylinder from the side view:
The metal canister (in my case its aluminum) screws onto the top of the master cylinder reservoir with a rubber gasket in between. And the red cap with the cork float screws on the other end of the metal canister.
The rubber gasket that came with the metal canister is too thin as it won’t seal the unit to the plastic reservoir. The canister is not an OEM version. Looks like someone custom made this.
The simple solution is to find a thicker rubber gasket. I need a 1-3/4" OD gasket that is 1/4" wide (thick). And it needs to hold up to brake fluid.
The more difficult solution and expensive to find an OEM canister. But after looking at Phil’s photo it looks like it pressure fits on top of the cap (?).
I think I need to find a rubber gasket or O-Ring the right size. Any suggestions?
Yes, but what screws onto that? A plastic cap/ brass adapter/ sovy can, or does the can screw on directly?
Show me the bottom of the can please 
Phil, here is the bottom of the metal canister (its threaded for receiving the male thread of the master cylinder reservoir).
The gasket is way too thin. I need a 1/4" wide rubber gasket or o-ring to seal.
Looks like someone has been busy on a lathe… totally custom solution… I wanted to see if you had the same sealing solution as the original, but obviously not. 
Could you use 2 or 3 of those seals? Looks to be a standard reservoir cap seal, Ray probably has them & I’m sure you have him on fast dial by now…
That’s what I thought Phil, custom made on a lathe. Great idea just not perfectly executed.
Multiple gaskets laid up together are a potential for leaks. Not a good idea, especially with brake fluid. I will have to hunt down the right size that can handle being emersed in brake fluid.
I could also put in on a lathe and fix the problem. Drew suggested that (he has a lathe) but I thought finding a gasket the right size might be easier.
Glen, here’s the bottom of a SOVY can (powder coated black, btw). A cap just like what’s on an oem
reservoir but with a hole in the middle and attached to the can. Nothing, as far as know, attaches to
the threaded fitting that you see inside the oem cap. Someone could have changed the fittings in
the past, but this was on my car since '78.
Greg, that is the detail I was looking for. Thanks. Now I see my canister isn’t even close to what the OEM was. The big question is does anyone have these anymore?
By the way, it’s a very strange design…
With all the gnashing of teeth and tearing of hair these things cause, I am starting to look more kindly on my Delta P valve.
Jon the Chief
Had to laugh at your comment Jon. Well, now I have two red top SAVOY float sensor caps. One with a “modified cork” but no metal canister to fit them in.
Anyone want to trade a canister for a red cap (the one that the cork is a bit modified) ?
Glen, I was waiting to dig through my parts before posting but I believe that I kept my old SOVY can & brass fitting after replacing mine with the one that I renovated (from TerryP).
Let me dig it out tonight & post pictures…
You will soon have all my spare parts… Service manual. Jack… SOVY can…
Phil, nice to know that you’ve been storing parts for me all these years 
Hope I can repay you one day!
Glen, here is what I have:
As you can see there is some surface rust on the top edge. What I did on my renovated unit (from Terry P) was sand blast then zinc coat. It’s only been a year but it still looks like new.
I’ll send a PM
Exactly what I am looking for Phil. PM responded to. Thanks once again for having a part I need !
Just a thought, I this day and age a cylinder with a male thread one end and female thread the other can be 3D printed?
If it was done in translucent plastic it would have a visible fluid level. I would bet Certified Lotus would have contacts that would know how.
Jon the Chief
Jon, your reading my mind. I needed an exact sample to scan 
Hello everybody,here the sandals man from holland.My federal elan chassis 8859 has also the tandem brake cylinder with this sofi system.Does anybody know how I can remove the fluid reservoir from the steel cylinder.I removed the 2 srews but I can not get it out.Must I use more power?
Regards
Willem
Yes. It’s a snap fit into the master cylinder and will require some prying.
there is a ring clip inside the front hole of the tandem master cylinder, holding the plastic tank on; I sort of remember having seen a manual stating that for removal one should turn it 45? and pop if off, but I found it rather hard (the plastic tank is 50 years old and getting just like myself, not as flexible as I used to be). Then I found a rubber gasket sealing the front feed to the master cylinder, probably cylindrical (or what was left of it), something that was not in rebuilt kits I’ve seen so far… it’s a non pressure gasket, yet if leaking you empty out the whole thing. The front tank feed has a conical fit to the master cylinder, but if there is some play (and the tank plus sovy make for quite a lever to hit over the years) that may not be sufficient to ensure sealing… For a tighter hold I’ve added a rislan tie around, clamping down the plastic tank onto the master cylinder.
Here is a picture, i am also looking for a metal canister if anyone has one to much please let me know…
