[TenTec] TT and staying on freq

[tlogan7 at cox.net]

Hi folks - 
I've owned a wonderful Omni C and an Omni V in the past. Soon a Corsair II will be arriving. They are all great rigs. The first two were serviced by Ten Tec. Neither was setup to be exactly on freq when they came back to me - which seems to be an almost humorous trait  of Ten Tec's earlier rigs (ya' love the rigs or hate 'em I guess). I expect the Corsair II to be off freq and drift as well. Can any one suggest what I can do to eliminate as much drift as possible and get the rig as dead on freq as possible? A rig like my Pro II is consistently dead on with no drift that I am aware of - but the technology is entirely different than the much older Corsair II. Any thoughts? Thanks folks.
73/Tim