Interesting concept Ned, I was going to ask that of Clarke Mfg, in the black tank it may be practically impossible to see any bubbling, the slight opacity of the yellow tank makes it possible to see the bubbles, but only just... they did show up well under the camera flash.
there were no quality issues raised in the first few years of production, they were used in Australasian safaris, and Rallye dos sertoes, and probably some other events..
Really hope they manage to sort the tooling glitch out !
Azza.