Cap on Brake Fluid Reservoir doesnt screw on

[Rocky]

As some may know from previous threads, I have just had a major service done on my 2006 Mazda6 Luxury Sport Hatch GG.
When checking the work this evening, I noticed that the Cap on the Brake Fluid Reservoir does not screw down - in spite of giving every appearance that it should. Has lugs that correspond with ones inside the reservoir but NO - it doesn't screw down. Just sits there.
There are numerous references on the net for this issue and the general conclusion is that it remains there by "suction" which sounds ridiculous but may be the case.
One guy duct-taped the cap on - which is what I have done - see photo - as I don't want it falling off between here and Brisbane tomorrow morning.
Any comments?

[KevGoat]

This thread https://www.mazda6club.com/threads/brake-fluid-reservoir-cap.219146/ mentions a redesigned cap is available from Mazda. Can't believe they left it in that state, though! There's no way I'd be relying on vacuum to hold it on.

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[greenMachine]

I'd look at replacing the whole reservoir, cap and all. Most of them just sit there secured by a clip, but you would need to find one that was the same size in bulk and in the dimensions where it attaches, and do it/have it done at a fluid change/flush. I'm surprised there is no discussion of this in the linked thread (was quick skim though).

[93_Clubman]

Haven't seen this type of brake master reservoir cap before - doesn't seem like the best approach to retaining fluid.
Have a good trip down, around & back from Brisbane.

[bruce]

I've never seen that style before. Looks like a spray can top.

[Red_Bullet]

It's important to prevent water vapour being absorbed into the brake fluid. This isn't like any cap I've seen before.

[Red_Bullet]

How does it prevent moisture from being absorbed from the atmosphere into the fluid? Got me buggered.

[Rocky]

Yeah, bloody disgraceful, actually. I mentioned it to the Dealer but of course who is to say I didn't "break it" when I checked the fluid post-service. It is such a poor design you could break it by breathing on it. In any case, they weren't coming in to it.
Bottom line - sh*t design and should have been replaced free - i.e. subject of a recall.
I have ordered a new one from Brisbane.