Waste Oil Heater Forum - Your definitive source for burning waste oil for heat.

I found a used Wedco Model L, rated at 200,000 btu, hung it in my shop and used it without any trouble for 3 seasons before this fall.  I always thought that I was getting away with something the way it worked without monkeying with it hardly at all.  But this season, it failed to stay running when I put the temp down to the minimum stat setting at night.' 
Knowing it hadn't had the maintenance that it should have, I took off both sides of the unit to give the heating chamber  a good cleaning.  I then pulled the injector out and cleaned it, checked the gap at the electrodes and made sure they were aligned as well as possible.  I'm able to see the spark when it fires, and I know there is oil present.  I'm
just not able to see the spray very well.  At the times I did have it showing a healthy flame, I could come back to check later and it would have changed to quite a degree, sometimes smaller flame, sometimes much bigger.  I found some junk in the opening right behind the injector nozzle, but I believe everything is out now.  I just haven't been able to get it to fire back up at all.  Any thoughts?  Thanks