GENESIS E-325 NOT GETTING FULLY HOT?

1 year old Genesis E325 bought locally new from hardware store here in Hawaii. They put it together and delivered it to us. All I had to do was buy and fill a LP tank. Its been fine until the other day. I have not used it in 3-4 months for various reasons and decided to smoke some salmon. My LP tank had shown low so I got it refilled and reinstalled. Grill started up fine but strangely it just could not get past 300 degrees with the top closed...even after 45 minutes? Inspected it and all burners appeared fully lit. No apparent issue with those. I have a grill flow meter installed between the grill and the tank. Looks fine and gas is clearly flowing but obviously there is an issue? This the first Weber gas grill I have owned and the first in at least 10 years. Not sure what/troubleshoot this issue. In the prior 9 months or so the grill would heat up to 500 or so degrees once started and with the top closed. I had all the burners running close to full out and it still could not get hot enough to even get my chips smoking. HELP! Aloha for all responses...I am a senior and a little leery of this grill now but it is convenient to use and I want to get it resolved especially now that I am feeling better and more attuned to cooking.