Gas Grill Igniter: Design Failure Therein

The Judges at the Trinity College Home Firefighting Robot contest use butane grill igniters to light the candles in the arenas, but the gadgets seem to have terrible reliability problems: very often, they simply don’t work. I brought a few deaders back to the Basement Laboratory this April and finally got around to tearing them apart.

It seems they don’t ignite because the trigger’s safety interlock mechanism shears the plastic gas hose against the fuel tank’s brass outlet tube:

Grill igniter with sheared gas tube
Grill igniter with sheared gas tube

I tried putting a small brass tube around the (shortened and re-seated) hose, but it turns out the trigger interlock slides into that space and depends on the hose bending out of the way:

Grill igniter with brass tubing
Grill igniter with brass tubing

So there’s no easy way to fix these things.

It seems to me that a device using flammable gas should not abrade its gas hose, but what do I know?