My mum use to sing it to me as a kid and her grandfather sang it to her as a kid and his grandmother sung it to him.. and so on
The right one to sing is.

I love to play my old banjo and rest it on my knee.
Now the strings are broken down; it is no good to me.
I took it to the mender's shop to see what he could do,
And now he's fixed my old banjo; it's now as good as new.

Then it goes into i lo-ve to play ay ay my oohhldd banjolo and relest it olon my knele etc etc :)