Check out GO2MARINE as they stock parts for various makes of LPG heaters. I just read this caption at their site.
So you have an old Force 10 heater - Read On:
The company "Force Heaters" made diesel, kerosene and propane models of the original "Force 10" heater. Dickinson (who also owns Sig Marine) bought out the Force Heaters and now makes a version of the original Force 10 to their own specs - called the "Cozy Cabin Heater". The Cozy Cabin Heater is only available in propane. If you own an original Force 10 Heater (there will be a badge on the heater saying "Force 10") and you have issues with the burner, regardless of fuel, then you will be limited to upgrading to the
New Propane Burner Assembly that fits both the Force 10 and the Cozy Cabin Heater. Regrettably, there are no burner parts available for the original Force 10 heaters.