Flame on gas grill is too small

Question

I have a 2004 Kenmore grill and I only get a small flame on the three burners even when it is turned up to high.

I have plenty of fuel in the tank and I made sure the tank was turned on.  Sears put the grill together and it never had a high flame.  Now I can't even grill a hamburger.  :(

Please help me.  It is a $90 fee just to come to the house.

Thank you,
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