Take the two wires off the vacuum switch and connect them together this will by pass the switch then try to burn above 2, let us know if that works.
Please explain what is happening if you burn above 2. I am assuming you are having same problem light blinking as before, if not let us know. As you increase the heat range the stove increases the vacuum. So you still have a leak or blockage somewhere in the system. If you have a barbecue brush lightly run it around the door seal to fluff the gasket. Check your hopper seal to see if there are any pellet or corn pieces jammed into the rubber. If you have some orange or red high heat silicone put some around the stirrer rod bushing as you do not use it. You might have to remove the exhaust blower and clean in that area sometime fly ash builds up in that area and just can not be cleaned without blower removal or the leaf blower trick. Just pulled a friends exhaust blower from a harmon, because he was getting the lost of vacuum and it is now running great.