Gorde,
You can obtain a Hurricane service manual from the ITR (International Thermal Research, makers of the Hurricane) website. However, if you can not determine the problem, give me a call and I will walk you through the diagnostic procedure.
The Hurricane heater is a very simple unit and easy to repair. The biggest problem with it is that since it's primary application is in the Marine industry most RV shops know nothing about the system, and try to through parts at it with the hope that it will work. This approach is often unsuccessful and always expensive. So take your time and determine what your problem is before replacing anything.
Gerald