Took me 5 hours to figure out my forge was running lean because of a spider nest
I kept getting a cold spot in the middle of my coal bed and couldn't get mild steel past orange, so I tore apart my whole blower setup and replaced the gate valve. Turned out a mud dauber had packed my air intake with nest and a dead spider, and the blower was just choking on its own air for who knows how long. I pulled the little screen off, cleaned it out with a wire brush and a shop vac, and the fire came right back to welding heat in two minutes. Now I'm paranoid about checking that intake before every session. Any of you cover your blower openings when the shop sits, or do you just deal with it when the fire acts up?
I had the same thing happen with a paper wasp making a nest in my side draft hood's air slot, and it took me way too long to find it. What worked for me was stuffing a rag in the intake and taping a piece of window screen over the blower outlet every time I shut down for the day. Cheap, takes ten seconds, and I haven't had a bug problem since. The screen still lets air through if I forget to pull the rag, so it never chokes the fire. Might be worth a try so you're not pulling things apart every time the heat drops.