Turn on,the closest tube only has a few lit - Weber Genesis Silver B Grill

turn off gas and unit immediately check and test for leak sputtering is air in line --valve clogging/failing --- wrong install --wrong orifice

If the tubes are lit, it's not a fuse problem.

V6 and V7 should be the 6L6's and V8 is the rectifier. The tube closest to the LARGE power transformer will be the rectifier as a check.

clean out the pilot with can of air or blowdown it with a tube do this when it it not alight pilot should be bigger

Make sure the pilot light flame is bathing the thermocouple; not too close, not out of the flame. If it seems in the right part of the pilot light flame, then the thermocouple may be failing; they only produce a few thousandths of a volt and it may be defective now. The thermocouple will look like a tube with a closed end and a thin tubing attached to it going to the regulator.

Check the burner tube closest to the pilot side of the burner tray. Is it burning a nice blue like all the rest? If it is not, clean out the jet on the manifold in front of the tube.

If it is ok, can you get a millivolt reading off the generator (thermocouple)? If so, get the reading with just the pilot on it, then with the burner load. Finally, watch that reading as the burners run for a while to be sure it climbs.

The only other thing I can think of would be to get manometer readings to verify gas pressures before and after the valve.

have you tried to heat up thermal couple for a couple of minutes. It takes a few minutes for the flames to actually starts heating thermal couple you might have to move thermal couple a little closer to heater flames

many of the newer furnaces don't have a standing pilot. look to see if you have a gas valve with a knob on top that says off pilot and on. look to see if a tube the size of a pencil comes out of the valve and goes down by one of the burners, look to see if there is a little gold piece of metal tubing protruding down to the opening of the larger tube . that is where you place the match. i prefer to use a grill lighter. safer and positive flame. turn knob to off wait 5 minutes for any gas to disipate. be sure your incoming gas valves are all open . usually at the meter and one at the furnace. usually the handle is in line with the pipe when open. from the off position, turn the knob on the furnace gas valve to pilot position and push down on it as you turn. this lets gas flow to the pilot tube by the burner where you have you flame starter lit and waiting. once pilot lights hold down on button for 3 minutes or less. longer is better to be sure the thermocouple senses flame . then gently release the downward pressure and the pilot should stay lit and you gently turn knob to on. if pilot goes out you may have a bad thermocouple. be especially careful if its lp or propane as that gas does not disipate like natural gas and can virtually lay on the floor till ignited. also consider having the heat exchanger checked by a pro with a carbon monoxide detector. they do crack after a few years and can be deadly when they do. good luck

How old is this set please?

The power relay driver or the relay itself is bad. Its sticking closed so the voltage is there for the power supply but the micro has turned off the tuner.