When you say VFO, are you referring to the raw heterodyne tuning ( 5mhz?)or the actual receive frequency.
THose radios were a favorite of CBers, so who knows what they might have done. There is a coil inside the VFO osc that gets messed with.
Maybe the fixed trim caps too.
There was some mod out there that did something the CB folks all tried to do and made a mess.