A top view of the AM FM Tuner from a IMA4406. As with the CD player, looks and be deceiving. A lot of the circuitry is on the bottom of the board.
These tuner modules were made by a Korean company which makes tuner modules mainly for car radios. These modules are not available to buy from NuTone or any other source that I can find. The manufacturer sells over 7 thousand different modules and there is no interest from them in selling just a few units at a time.
Our only source for these parts are from donor intercoms.
One problem with the design of the IM/IMA4406 is that a failed tuner module and supporting components can cause the entire IM/IMA4406 to become non-operational.