In article .com,
"stol" wrote:

I don't think Randolph made the alcohol resistant sealer 18 years ago.
It is part # 912 I think. If it the old stuff and you ran auto fuel in
it that was a mixture of gas/alcohol the blistering is what usually
happens. I have a Zenith 801 and I would dread to have to unzip my
wings to get at the tanks. We all feal your pain....

Randolph 912 is white; the non-alcohol-resistant stuff (Randolph 911) is
yellow. IIRC, the best way to remove the old stuff is to slosh some MEK
around the tank to loosen up and dissolve the old stuff.

You have to do this several times, then re-slosh with 912.

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