Missed this... I thought you meant it were the solenoid valves that failed. and I was worried about that, maybe a different fuel composition. The very very first solenoid valve I bought was used with glowfuel and failed after a few years of storage, but the ones used for gasoline never failed, ever,

I do not know why Seeeduino electronics fail, I have heard once or twice that Hans' electronics failed, but that always turned out to be accidental short-circuits or reversed polarity issues, never from just storage.
It could have to do with the memory of Seeduino processors being volatile, perhaps? Did you try re-programming (flashing?) them? just a suggestion.

Anyway, the valve that Chris came up with, would really solve the entire issue, and make things MUCH more affordable. Both financially (which is NOT the main issue) but much more important, technically.
Anyone can improvise a small servo-operated airvalve even with oldfashioned materials.

I mean, if I had to, I could make one out of a tiny block of wood, a piece of 2,5 mm internal diameter brass tubing and basically an old rusty nail ground to a cone shape. Wouldn't look nice, wouldn't be compact, but it WOULD most definitely function.

And THAT is what I like most about Chris' new idea!

The downside is that it does not have the atmospheric compensation, which I particularly liked for keeping the planes cleaner, but that is a very small price to pay for the accessibility of this design.