If the speaker gets too hot, then the speaker will shut down and display hOt on the display. (I think you also get another light on the right-hand side that indicates thermal protection)

You should be able to go into the setup of the speaker (Type 0) and cycle through the settings to set the internal ambient temperature for thermal protection (defaults to 24 degrees)

Check the temperature of the rear panels of both speakers (if the failing one is hotter than the other, then that may indicate other issues).

It is unlikely to be the tweeter; it is more likely that it could be the DSP or amplifier boards.

Drop me a PM if you're still having issues.

Cheers,

Steve

Main: 861v6 (LPS), 808v6, UHD722, DSP8000SE Anniversaries, DSP5200.2HC, DSP7200.2, SW1600, Sky Q, Cambridge Audio BD, Roon, M80
Office: 861v4 (LPS), 818v3, 800v4, HD621, M&K S150P, DSP5500HC, M&K MPS2810 sub x2
Son's system: 861v4, HD621, DSP6000.2, DSP5200HC, DSP33
Spare: MCD, 100 Series, 200 Series, 500 Series, F80s, C15s.