According to "Connecting To Connecticut" by Betty Jean Morrison, pg. 10, the Probate Office there only carries probate records from 1834 to the present.
The Barkhamstead Probate Office is located at 67 Ripley Road, P.O. Box 185, Pleasant Valley, CT 06063, (860) 379-8665, open 10-1 Monday - Wednesday 10 am - 1 pm (And by Appointment) They may be able to give you more specific information about the existence or location of earlier records, but I suspect that if there are existing records they may be at the Connecticut State Library, on microfilm.
It may be worth your while to get in touch with them, as well as ask the CSL Perhaps someone nearby can take a look for you.