Roger Long wrote:
We have an MX300 in our 172 that has started producing squeals and static
whenever it is turned on. ....
Is it worth sending it back to the factory for overhaul or should we just
turn it directly into a paperweight and live with one radio until we can
afford another?

TKM radios can only be serviced at the factory.

I would send it in, get a repair estimate, and make your decision
accordingly. It seems as though it would be worth wagering the
postage, esp. if you're considering living w/ one radio for longer
duration.

FWIW,
Sydney