Despite a library just a county or two over from me having the sheet music to this song, the inter library loan came all the way from Idaho! However, I can confirm that this was the requested song.

Here's how it was printed in H. W. Hanemann's Soft boiled ballads: a collection of heart-wrecking songs, pages not numbered. The song was given a copyright date of 1931, meaning it has entered the public domain.

THE SLUG IN THE SLOT MACHINE
(H. W. Hanemann)

In a gloomy cell in Sing-Sing there sat a handsome lad;
Though young, his sad career had lined his face.
Unpracticed eyes could tell at once his ethics they were bad,
Or what would he be doing in that place?
"How have you came to fall so low"? a social worker cried,
And as he pinched the worker's watch, the handsome youth replied:

REFRAIN
"I put a slug in gum machine, in the happy long ago.
It seemed at the time, more a lark than a crime.
But how was I to know?
Success made me bold and ambitious,
I soon was socking gents on the bean;
So it's due to the gum,
That I am a bum!
Curse that slug in the slot machine!