It's getting cold here....so I went to fire up the natural gas
fired space heater in my basement. The pilot would light but go
out when I released the control knob.

So...I replaced the thermocouple. Every so many years, it seems
to need it. However, this did not solve the problem.

Preheating the thermocouple made the pilot stay on. For about
two minutes.

I can't really see into the pilot compartment when I'm holding
the knob down. Using a mirror did not help much. It looks as if
the pilot flame is not hitting the thermocouple; it's "leaking"
to the right side.

The pilot unit is pretty standard stuff, the thermocouple is on
the left, parallel to and separated from the pilot by about half
an inch. The whole assembly is rotated about 20 degrees from
vertical, about 11 o'clock. The pilot orifice faces what I would
call a "deflector" that bends the flame towards the thermocouple
and also has a "v" assembly that routes the flame around the
thermocouple.

It looks as if the flame is not being directed towards the
thermocouple and is just randomly burning around the deflector. I
have cleaned this as best as I can, poked and prodded, chipped
and scraped, with no help.

The only thing left I can think of is that the orifice itself is
partially obstructed. Is there any way to clean this without
damage and without disassembling the whole heater? Is there
something else that would cause this problem?

PB