The current "red label" ATS-505 that I own has a bad encoder. I bought a replacement online, but it needs to be modified to work with the radio. The DX-398 has a deteriorated magnet in the speaker (common problem). My initial plan is to use the speaker from the ATS-505 "red label" for the DX-398.
I don't know if I will eventually repair the "red label" ATS-505 or just use it for parts in the DX-398 since many of the components are the same.
The good news is that I will be able to provide more content to you including modifications, enhancements, and repair information! Stay tuned!