Need help locating general liability insurance

I am seeking pointers for obtaining general business liability
insurance for a vehicle inspection business.  Consider this analagous
to a home inspection service, where an inspector inspects and
documents the condition of real estate.  Our business provides this
service for vehicles (cars, trucks, motor homes, etc).  Primary
customers are used car buyers/sellers, mechanical warranty companies
(to verify mechanical repair claims), etc.

For some reason, insurers think the process of inspecting a vehicle is
too risky to insure for general liability.  I'm not seeking Errors and
Omissions insurance, just coverage for losses that could be incurred
during the process of an inspection (which does NOT include repair or
dismantling, but simply an inspection to verify condition, with
digital photography to document the vehicle ID and condition).

Can anyone help or point me in the right direction?

KHC