To Pull Out All the Stops

choi

"means to make every possible effort or use all available resources to achieve an end.  The 'stops' in question were originally the physical stop knobs of a pipe organ. * * * The stop knobs open and close the stops, which control the flow of air into the pipes. A key plays all of the pipes in one rank"
https://www.merriam-webster.com/ ... -history-pipe-organ

My comment: There is no need to read the rest, which is confusing to a layman like me.

(2) A picture is worth a thousand words.

How a Pipe Organ Works. American Public Media, undated (under "PipeDreams®").
https://pipedreams.publicradio.o ... ipeorganworks.shtml

My comment:
(a) View the graphic and paragraph 1 only. The bottom of a pipe is "toe" which has a hole -- to be connected to wind chamber (number 3 in the graphic), if a slider allows it. A slider (number 6 in the graphic) contains a series of holes in a line -- for a series of pipes (that series is called "rank" in jargon). If a hole in a slider does not correspond to a pipe, that particular pipe receive no air, and hence produce no sound. A pipe in a pipe organ is identical acoustically to a fife, where air vibration creates sound. A pipe in a pipe organ has only one stop, not many stops.
(i) The description here is for all types of (musical) organs, not just pipe organs.
(b) The phrase to pull out all the stops, means pull out all stop knobs of one organ, letting all pipes in action (if and only if the corresponding key is pressed).

(c) If and only if you are interested in the mechanics of organ and want to know more, you can read the main portion of

Renee Montagne, Organ Music: Pulling Out All the Stops. NPR, June 5, 2006
https://www.npr.org/2006/06/05/5 ... g-out-all-the-stops
("Book Excerpt: 'The NPR Classical Music Companion' [by] MILES HOFFMAN * * * To play the instrument [organ], the organist uses keyboards and pedals. The pedals are like an extra set of keys, but played with the feet. (Their function is not in any way related to that of piano pedals. [in fact, keys in organ and piano are different functionally: pressing a piano key strikes a chord -- varying force on a piano key makes a difference but not a organ key) In fact the keys and pedals are really just one end of a system of valves that open and close the pipes at the bottom, allowing forced air in or shutting it out")

(b) American Public Media
https://en.wikipedia.org/wiki/American_Public_Media
(2004- ; is the second largest producer and distributor of public radio programs in the United States after NPR; Based in St Paul, Minnesota; Parent  [non-profit] American Public Media Group)