Found at Becky's (Dragon's) Guiding Resource Centre:

BANJO SONG

I Used to hAve an Old banjO, that rEsted On my kneE.
But nOw the stRings are brOken doWn, it's nO more uSe to mE.
I toOk it tO the meNder shOp, to seE what hE could dO.
He saiD the striNgs are brOken doWn. It's nO more uSe to yoU.

The second time you sing it, to put a "llll" sound at every capitalized letter. You can also try adding multiple "llll's" or singing the song faster and faster each time.

While the above verse is the original song, I have recently come across a second version. Thanks to Megan Burns for sharing this with me!

I used to play on my banjo, but my banjo was broke.
I took it to a banjo shop, but the banjo shop was closed.
So I took it to another shop to see what they could do.
They fixed the strings on my banjo, and now they're good as new.

* * *

Another copy, from Girl Guides of Canada, Oshawa Division, Guiding Gateway:

BANJO SONG

(The key to this song is to sound like a banjo by altering the words..
I u-dooloo-sed to ha- delave an o-delo banjo-delo...)

I used to have an old banjo, that rested on my knee.
But now the strings are broken down, it's no more use to me.

I took it to the menders shop, to see what he could do.
He said the strings are broken down, it's no more use to you.


[In my experience, once a song gets established as a "scout song" or "campfire song" any traces of its previous existence are lost! (Though there are a few exceptions.)--JD]