[WriteLog] 765 mark tone adjustment?

[KG8DH@aol.com]

Alright folks, anyone have any idea where the mark frequency can be adjusted 
on the 765.  Don, AA5AU, suggested that I adjust it as my transmit frequency 
and receive frequency vary about 100 hz in tone, and in operating this past 
weekend, I had several contacts have to move to decode my signal.  Not a good 
thing!  I looked through my owners manual, and I can't find one word about 
adjusting the tone.  If anyone has an idea where this is at, I would 
appreciate it.  
Thanks
Geary
KG8DH