Based on the diagrams I have viewed, the white wire at the box retards the timing. One of the diagrams showed the white and red flipped at the plug. Perhaps it depends on where the red wire is referenced in the circuit. Or it is a mistake in the drawing.:

https://www.carbdford.com/fletch/tech/duraspark/duraspark.htm

What heads are being used in this instance? Possibly a head issue not a HS issue?

Try a higher quality penetrating oil just about anything is better than wd40 for this type of effort, pb blaster, liquid wrench, Kroil, et

I ordered directly from amk for the first time a couple of weeks ago. Same experience as you. Placed another order this week.

Had a couple of long conversation with my independent insurance rep a couple of months ag. Our home owners went up $2000 this year, with Safeco. He tried to find a better rate with other providers and well as rewriting my policy with safeco. The best option was to continue with the renewal. Apparently the state legislature has changed the minimum deductible to 2%. Rewriting my policy or moving to another provider would change my deductible to 2%. The good news is the minimum deductible is moving to 5%!!! I purchased my house for $300k in 2015. The housing market has gone crazy here in the DFW area. The tax man says my house is valued at over $600k. I just do t see it… At 5% my deductible will be north of $30k! In short we will be paying higher rates for overpriced homes, high deductibles with no insurance benefit unless the house burns to the ground…

If the system does not have the capacity a lower thermostat would only delay the inevitable.

What temp do you consider overheating? What is the highest temp you have see?

You may not be getting enough heat. If not using MAPP gas, go to the home store & grab a yellow bottle. MAPP will provide more heat.