Well like you said but in different words, this takes a tech. One speaker could be half blown. And in a guitar amp post people would not notice much if the amp is only pushing one direction.

I say let the guy do it. I think he owns it. If it goes poof then it does.

Maybe the guy will buy a scope. I think novices should always start with a CRO, not a raster based one. No digital no nothing.

That would ell of the speakers. They both had the same power but one (the right one I think right ?) is half ****ed up because maybe something got spilled in it. **** happens.

Well if out OPer here is reading he is probably learning. One of the simplest tests would be to switch the speakers. However we know that is not always feasible. You got two viable choices, mount them reverse. Or just hook it to external speakers. We all have a pair of speakers around.

So without a scope he is not even to that point yet, needs a pair.