[Elecraft] My T1 is malfing. What do four yellow flashed mean?

[Chuck MacCluer]

My venerable T1 has suddenly taken ill. After many left button long
presses, it finally goes into tuning mode. I tune. Some random time later
it will drop out of tune as the yellow LED resumes its series of four
flashes.

Did a cosmic ray kill some critical flip flop in the CPU or is there a
simple explanation? What does four flashes mean?

Chuck w8mqw