Which is why there can be no infinite regress of secondary causes. An infinite chain of secondary causes would by definition have no primary cause, and thus there would be no effect. But there is an effect, so there must be a primary cause.

There's nothing about there being an effect which implies a primary cause. The only thing an effect implies is a preceding cause. You can reject infinite regress but cannot do so on the basis that there must be a primary cause for that is circular. Once you admit an infinite universe there is nothing that prevents an infinite regress.

Not only am I treating it seriously, I've said many times now that the contingency argument agrees that the universe is infinitely old.

You may have said that but the universe being infinitely old might as well have not even been a footnote in your argument since it doesn't appear that it's infinite aspect applies in any way to your reasoning, when in fact it should. There is a distinction in the implications between whether the universe is infinite in time or finite. For some reason you're treating the two cases the same.

The contingency argument says nothing about any "beginning" or "cause" for "the universe."

But it does because it's based on dependence, and dependencies are communicated through causes. How else would you say something depends on something else?

"My position is that if the log cabin is infinitely old the lamp doesn't need a power source." Does that make any sense? Clearly not.

If the universe is undergoing cyclic expansion and contraction then internally the total energy may be zero but there may be gradients inside of it where energy can used for work. If the universe expands and then contracts again ad infinitum then the power source merely arises do to gradients inside of it. Why do we need a power source for the universe? Why do you need a power source for the existence of quantum fields? I don't see how any of that follows.

As I was telling someone else, when you turn on a light you do not cause there to be an electromagnetic field, you simply disturb the field that already exists. When you throw a rock into a pond you do not cause a pond to exist you just disturb it and produce waves. Your argument about the power source does not have anything to say about if the existence of the electromagnetic field needs to be dependent on anything non-contingent. It was not caused when you turn on the lamp, the lamp just shakes the field and causes ripples in it (light). Why think that the field itself is caused? We can't the field exist eternally? (technically the field arises from symmetry breaking but I don't feel it's pertinent to the argument)