[TenTec] Off frequency Omni VI

[John King]

Fellow Ten Tec  owners, I have an Omni VI with factory upgrade and no one else has ever worked on it or adjusted except for an S meter replacement that I did. It is my favorite of all my rigs including Kenwoods and Icoms.
It has come to my attention that the frequency has shifted downward about 89 hz. I call a net on 3.925 mhz and I set the dial to 3.924.91 . According to WWV and my other solid state rigs the OMNI VI is off by that amount on all bands when checked on LSB. No checks have been made on USB.
I don't know which trimmer to adjust that sets a frequency for all bands. Until I am certain which trimmer and where exactly it is located, I will NOT Touch anything inside. The modular board construction is confusing  for an old geezer like me. Dou you have input? Thanks and 73, John, K5PGW