I am having difficulty identifying verb modifiers from noun

I understand your explanation, but it doesn't apply to GMAT strategy or to American English. And practically speaking, it's causing more confusion than clarity! Let me suggest another way to think about modifiers that might be more useful.

As you note, both "based" and "using" are participles that are derived from verbs, and they both modify nouns ("verdict" and "engineer"). There's no contradiction here, and on the GMAT, you should prioritize putting the modifier next to the thing it describes, unless it's a participial modifier at the end of a sentence. This is the simplest rule of thumb to follow when it comes to SC modifiers, and you don't have to worry about the distinction between noun and verb modifiers.

For example, "The engineer solved the problem using the technology" is perfectly appropriate because the modifier "using the technology" is a participial modifier at the end of the sentence. It applies to the grammatical subject of the sentence. But the passive "Using the technology, the problem was solved by the engineer" is wrong because the modifier now applies to the object of the sentence instead of the subject. A better choice would be to use a relative clause modifer: "The problem was solved by the engineer, who used the technology."

Perhaps the confusion is coming in because of the terms "verb modifier" and "noun modifier." A verb modifier modifies a verb, but doesn't necessarily contain a verb itself. For example, an adverb like "quickly" is a verb modifier. A noun modifier modifies a noun, but doesn't necessarily contain a noun itself. For example, an adjective like "tall" is a noun modifier.

Hope that helps!

Thanks for following up Mimi.

Looks like I have been assuming "Using the technology, the problem was solved by the engineer" is correct (although not active enough.. which is not always a reason for rejection on the GMAT right?). Whereas, you say in your reply that this is incorrect as Using the technology should touch the engineer noun. This is the part that confuses me. Per what I read, verb modifiers do not need to touch the nouns they modify.

So the question becomes.. which of the following are correct/incorrect:

1. Verb modifier, object.. passive-action.. subject
2. Noun modifier, subject.. active-action.. object

I know #2 is correct, but #1? Can I assume that #1 will also always be incorrect for the GMAT? (This tells me that if you have a modifier at the start of the sentence, separated from the modified noun by a comma, it MUST touch that noun/subject except if it is an absolute phrase like - His head held high, Owen walked out the door.. where technically the modifier modifies the entire 2nd half of the sentence and not just Owen).