If just a few teeth are very worn or missing, you can replace them by filing out the remains of the old teeth to leave a trapezoidal gap. File a piece of brass so that it will dovetail into the gap, then solder it in place. File the new piece to the profile of the missing teeth. The strength of this repair is in the dovetail, not the solder, so make sure it is a tight fit.

Dismantling The Burner
If either of the pinions is worn, this will entail removal of the gear bracket. To do this it is first necessary to remove the washer that secures the inner end of the wick knob shaft. This may be soldered or the end of the shaft riveted over. If it is soldered, melt the solder with a micro blowtorch, then tap the burner gently on the bench to dislodge the solder. The washer can now be prised off with a thin-bladed jewellers’ screwdriver. If it is riveted, file down the riveting on the sides of the shaft (not the end) with a needle file until the washer can be prised off with a screwdriver. When the washer has been removed, pull back the knob shaft so the gear bracket can be removed.
The gear bracket is soldered to the burner at the bottom (tab that pokes out next to the rack) and at the top is secured to the side of the burner in one of two ways:

a) Spot weld (almost invisible).

b) solder (there is a rectangular hole in the side of the burner and a small tab punched out of the gear bracket that pokes through and is bent over.

If the gear bracket is soldered top and bottom, prise up the top tab with a small screwdriver and de-solder top and bottom. The gear bracket can then be manoeuvred out. If the top of the gear bracket is spot-welded, drive a small, sharp chisel or sharpened screwdriver blade between the gear bracket and the side of the burner to break the welds, then de-solder the bottom fixing. On re-assembly you will have to solder the top fixing.