Find a competent watchmaker. He'll either accept the job or he won't. $750 every 5 years (and the cost will be more 5 years from now and more again the next service) is a ridiculous price to pay for simply servicing (cleaning and lubing) a chronograph. Even a coaxial.
With all due respect, and I mean that sincerely, the Coaxial requirements are not something for just a "competent watchmaker". The misapplication of lubricant (to much or too little) alone can lead to premature stoppage. Al from Archer watches (he posts on both WatchUSeek and the OmegaForums websites) can give detailed reasons for the need of specialized training and equipment for these escapements.