Garage heater question.

I have two wall mount heaters in my garage, one is older than the other.  The older one fires up with difficulty, runs for a bit  and shuts down.  I noticed the flame on the pilot is small and sometimes flutters like it's starving for gas (all of this is propane).   Once running, do you need a pilot?

Does it need cleaning?  I don't have manuals for these so if you have any idea, it's better than what I have.

Thanx.

Pilot light tube is dirty. If it does not have a steady pilot light it shuts off. 

Yep, what Steve_Jones says.     Most pilot lights have a little hole on the side to shoot out a small flame that heats up a thermocouple.  That thermocouple is the safety, if the temperature drops on it, it cuts the gas supply. 

My guess is that the thermocouple is getting juuuuusssssttt warm enough to start the thing, then, after the new flames start and cool air is being drawn in near it, it'll cool down enough to trip the safety and cut the gas.

A bad tank of propane caused this behavior on one of my Mr. Heaters.  It gummed up.  Fortunately all I needed was a new propane tank and it sorted itself out.

Thanks.  So, pipe cleaner, Q-Tip?  I can't see how long the tube is.

I used compressed air.

Thanks folks.  I put a 6" length of welding wire down there (it was off) and swirled it around a bit in each hole.  It's better but the pilot is still twitchy.  Later I will kill the propane at the inside valve and blow the lines with 120 psi.  Kill it or Cure it.  =~ 0

Oh yeah, the Mr Heater guys say to use a part of a rolled up dollar bill.

I have replaced the pilot light assembly on a few of those ventless heaters.  For the $18 for the part, I'd rather just replace it than have to disassemble it twice if cleaning wasn't a good fix.