Hi All, Two K3s in the ZM1A shack, #320 and #321 - both have the Revision B March 15 2009 modification. Recently, #321 has refused to turn off - no problem with #320. Checked the 1N4148 diode, tests OK but replaced it anyway. #321 still refuses to turn off. Has anyone else experienced this problem? 73, Ken ZL1AIH (at ZM1A in contests)