Novemberico and I went to 1A a couple times in 2008-2009. We free-climbed down using the corrugated sides of the shaft and misc. piping and superstructure as handholds.
In retrospect that was a ridiculous plan and we're lucky neither of us fucking died. 20-year-old me was a
lot more reckless.
But as scary as the climb was, it's squeezing though the blast valve that really stuck with me as totally sucking balls. I remember it being secured pretty well but dang that was a tight fit.
This is the only photo I can find from those trips-