Hi dkoe:
The US firm LoDuca Bros. from the middle 40s to the middle 70s did not produce accordions but imported them from Italian manufactures with their badge applied.
The Badge LoDuca Bros only means the importer and not the Italian manufacture.
Some LoDucas had treble keys that were keyed in (not unlike Hohner) and held with a visible spring and keyed and removable from the base keyboard.
And then their were models with treble keys held by a spindle with a spring mounted below.
And again their were models with keys held with a spindle but with an exterior spring.
Some of these old LoDucas were of fine semi-pro quality and some were just of mediocre quality and with age not worth repairing.
A pic of yours will help , and if not take a look here to match what you have --
https://www.google.com/search?q=lo+...=7UgvV_7rNcTxmQGT3YH4Ag#imgrc=BM1CMxNqo3336M: