I need a brake fluid resevoir cap...Where can I get one?

I tried to bleed my brakes today on my 2004 360 F1 using my Motive brake bleeder tool.
I attempted to use the adaptor#1100 that is recommended by the manufacturer of the brake bleeder. For some reason, the threads did not match up. It felt like the cap was starting to thread on properly, but as soon as it started to engage, it felt hard to turn and it jumped the threads. I called Motive and asked about my issue. The guy said that some Ferraris for some reason don't work with the #1100 adaptor, so he told me that if I send him a spare cap for my reservoir, he will alter the cap and make an adaptor for the bleeder for me using the cap. The only problem is that I'm having a lot of trouble finding a cap to send him! The best I could do is find the whole reservoir and cap sold as a unit for approx. $120.
I didn't want to spend that much and buy the whole tank. Does anyone have any idea where I can buy just the cap?

Oh, by the way, there is a rubber button in the center of the cap, what is that button there for?

 

The cap has an attached float device and wiring for the sensor. The top center has a rubber button on it that says something to the effect of "push to test" or something like that...

See above response.

I'm very confused. My first step in solving my issue is that I bought a used reservoir and cap from awparts. I'm going to see if it is the same setup that I have and if it is, I'm going to send the cap to the company that makes the Motive bleeder and they will alter the cap to work with my bleeder. I'll keep you guys posted on my success (or lack of).

 

Here is a picture of the Brake reservoir cap that I purchased. The rubber button on top is visible in the photo. After looking at it carefully, it appears that the float is attached to the orange rod. When I push the button while holding the rod, I can feel the rod under the rubber button. I have to guess that it is designed to be pushed in order to get an accurate level reading. If the float gets a little stuck and the level drops, the brake fluid level will appear correct until the button is pressed and the orange rod is pushed down, allowing the float to move down and have an accurate reading. I hope that makes sense, and it's just a guess.
I already sent the cap to Motive Products so they can alter the cap to work as a bleeder for my car. I will post the outcome.
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I have to hope that they tested it when they made it. I will obviously try it with an empty bleeder tank at first, just to make sure that it doesn't fail. If it fails, that would be a very bad thing! The guy told me that they have done the same thing for someone else that owns a Ferrari, and it worked perfectly for him.

Please post back to let us know how it worked out. Hopefully it seals ok and hooks up to the Motive quick release. If I don't trust the cap that they made me, I may buy one of those too.

 

I have the Porsche cap. It works perfectly on my 911, but it will not tighten on the Ferrari. I have no idea why, it is supposed to work.

 

The altered cap arrived.
I will update you guys on how effectively it works.
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It worked out beautifully!
I did however run into a non related issue, but I'll start a new thread asking for advice.
Here is the new thread:
http://www.ferrarichat.com/forum/technical-q-sponsored-algar-ferrari/468291-bled-brakes-today-ran-into-issue.html#post143536328
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