Wick Raiser Repairs
Repairs to the wick mechanism are more problematical, but not impossible. However, a certain amount of metalworking skill is required.
I have seen three main failure modes:

a) rack teeth worn due to excessive play between rack and guide channel. Usually the tops of the teeth are burred.

b) rack driving pinion stripped.

c) slippage between rack driving pinion and the larger gear.

d) pinion on wick knob shaft stripped.

Rack Repairs

If only the rack teeth are slightly worn, you can often repair them by:

1. Filing tops of all teeth down to height of lowest tooth.

2. If the teeth are very worn, cut down between them with a hacksaw to increase tooth depth. Don’t cut so far as to weaken the rack.

3. Re-profile the tops of the teeth with a file.

4. Replace the rack and pack out the guide channel with a brass shim strip to hold the rack against the pinion. If the gear bracket is still in situ, you will need to form a hook on one end of the packing strip. Slide the strip down the rack guide channel, and hook it over the bottom edge. Then bend over the top end of the packing strip.