Have you tried checking your gas pressure? This is ez to do. Go to yahoo and
type in "manometer". This device can be made for a couple of dollars, and
instructions come with the plans to make it.. It hooks up to the gas
regulator. Just turn the screw with a screwdriver bit turned backwards and
the pressure will change. Maybe yours has loosened up and let the pressure
down a bit. Unscrewing this disk lowers the pressure, and bumpy roads and
such for 20 plus years can do this.

Brass does not oxidize much, but it does oxidize. That hole is so small that
it can make a difference. You may be able to compensate by squirting some
diluted battery acid through the hole and rinsing.