Conn-Selmer is suing the founder of Woodwind and Brasswind.
The Elkhart based music company claims Dennis Bamber failed to pay back credit from a 1992 agreement.
The 3.5 million dollar lawsuit was filed this week in South Bend.
Conn-Selmer's parent company, Steinway Music, backed out of a deal in January to buy Woodwind and Brasswind, which is located in South Bend.
Last year, Woodwind and Brasswind filed for bankruptcy protection.