I have a Kenwood 440SAT which is failing.... Any suggestions?

How is the 440SAT failing? Any chance of repairing it or selling it as-is?

Ignoring the "bouncy" buttons, everything works fine on CW but won't
modulate. Microphone may have failed, and I haven't gotten around
to cobbling a substitute to the right connector.

FWIW, I realized today that I DO have full manuals and have learned that,
even though the AT can be an after-market addition, the schematics show
the AT is controlled by the radio's processor and making it work without
the radio will be a real pain!
--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
NRA Life Member & Certified Instructor for Rifle, Pistol, & Home Firearm Safety
Also Certified Instructor for the Kansas Concealed-Carry Handgun (CCH) license