Prepare Gas BBQ for the Summer

First preparation step, remove all briquettes from inside the BBQ. Next, remove the racks and burner or burners. Clean the entire inside of the BBQ. There are chemicals, which can help to clean off last years left over spills & burn ones. I prefer a wire brush, scrapper and some good old-fashioned elbow grease. (Physical Work)
Wire brush the burner(s) and rack(s) and flush with water. Clean out the holes or slots in the burner(s). A wire from the brush, large pin, needle or thin wire works best, in my opinion.
Also check inside and down the burner tube. You may find a spider web. If so, a coat hanger wire works to remove it or a bottle brush. Next item to check is for s spider web inside the orifice. The orifice will be the brass or bronze thimble hex nut the burner tube sit on or over. Use a flashlight if needed, to peer down the tiny hole in the center of the orifice.

Spider webs inside burners or orifices is the number one cause of low burner flames at the burners or not gas to the burner (s) If you see a white web or what appears to be a tiny cotton obstruction in the orifice, it's a spiders web. Not uncommon to find spiders in either the burner tube or the orifices.
To remove a web from an orifice, I suggest either removing the orifice or using a pipe cleaner. To effectively remove a web from an orifice, it helps to have the gas to that burner on.
Turn on the valve to the effected burner, insert the pipe cleaner, twirl it around and pull it out. Done correctly, out will come the web or it will be loosened enough to blow out from the gas pressure.
TIP 1:

In some cases it helps to clean off a bit of the pipe cleaners outside covering by burning it off. Than slightly untwist the thinner wire from the thicker one. Insert into orifice, twist and remove. Out should come the web. If the web does not come out in the above manner, gets pushed down further, orifice removal is required. Use a 7/16-inch open-ended wrench. Turn counter clock wise to remove. Clean and reinstall turning clockwise.
TIP 2: Helps to count the number of turns it takes to remove the orifice. Reinstall fully till it bottoms out, than unscrew out the number of turns to reset it back to it's original position.
Clean racks using wire brush. Cleaner not recommend but may be used if rinsed well. BBQ cleaner, wire brushes, etc available at most local hardware stores or any appliance parts stores.
Tip 3: Suggested replacement of briquettes is yearly but may not be depending upon prior usage, physical condition and cleanliness. Cleaning can be done, on some types of briquettes, by washing and drying.
Another method is to incinerate briquettes after cleaning and reassembling BBQ. Why not. You need to test the BBQ anyway.
If BBQ parts are required for replacement, write down the bran name, model and serial numbers, visit the local appliance parts store(s) in you area. Bound to have the parts.