[Elecraft] K2 Sidetone help

[Mike Furrey]

Hi All!A few months ago I acquired a used K2, s/n 13xx, firmware 2.04, and the sidetone setting is U8-2 but I do not have any sidetone and no matter which hoop I jump through in the menu system, I cannot get the sidetone to function. The radio would not let me make the change to U6-25 no matter what I did.  I made a couple of CW Qs but I listened to the sidetone on an external keyer. I have also made a few SSB Qs today during the CQWW SSB contest, all QRP. All aspects of this radio performs as they should ... except for the sidetone. 

>From all the paper work, I am the forth owner of this radio and I don't think any of the previous owners ever operated CW. The rig did have a defective key jack that I replaced. It does appear that this radio has had all the updates performed. So, I am at a loss ... I have dog-eared the manual and have searched the mail archives for clues and procedures to enable the sidetone but I have yet to be successful. 

I am hoping for a few suggestions/hints before I go deep into it with the test equipment.
Many Thanks, Mike WA5POK - owner of thee K3s and now this K2