This means that you can't see/understand a "particular" matter properly?

Yes, I guess so. Probably, some sort of void or unclear area in the perception/understanding of something, thus, a blind spot (you know, the blind spot in the retina created by the abscence of photoreceptor cells in the point where the optic nerve reaches the retina... although, probably in the context where you took it from, it was said in a figurative way, not referring to the eye).

I think this classifies as a "sort of". The blind spot refers to something you cannot see. So, for example, all the kids in your neighbourhood are young hooligans and you know it - but the only kid you think is not a hooligan is your own kid. You have a blind spot where your own kid is concerned. Just an example, but hopefully illustrative.

A few more examples from brianL's "Lurn Yersel Tuh Talk Proper":
"Hast heared o'er?" = Have you heard about?
"Ahm goin down on't throad fer summat." = I'm going shopping.
"Thall gi thissen bellywarch!" = You're going to upset your digestive system!
"Wurr hast bin?" = Where have you been?

Not a million miles from Cumbrian ... so would you understand "Ast ivver seen cuddy jump ower five bar gat?" Brian?

Yeah, more or less. Not sure about "cuddy", though.

I figure there's a lot of Viking-speak left in both areas. A cuddy is a cow; makes sense as a cud-chewing animal.

I guessed it might be a cow. Actually, there's very few, if any, who use genuine Lancashire dialect words (such as "bellywarch") in Oldham. I have an accent, but only use dialect on LQ.

If I don't lurn tuh talk proper, at least I'm sure I'll lurn tuh rite proper (or should I rite "propah" instead?)

Dialect, along with strong accents, have mostly disappeared with the spread of wide area communications, starting with newspapers and going on to radio and TV. That is a cultural loss of diversity; dialects are becoming a historical curiosity.

Those of us who are old enough to remember dialect in commoner use enjoyed an expressive vocabulary, built on language history. What now of "laiking" for "playing" because "playing" means "not working"? Of describing someone as "flarchy"? Of my friend from Wigton in Cumberland who went travelling overland to India in the '70s and came back without his local language and, when asked why he had changed, said "Eh, man -- nobody understood me!"?

As a child we accept the words we encounter then learn some are not "proper". I assumed they were local dialect until most of the words I took for dialect in the streets and playgrounds of Carlisle turned out to be Indian words collected by the Border Regiment on its thousands of man-years of duty in India. Truly language is living history

Propah? That sounds like Cockney to me. We sound our r's here up North.

Yeah, it's a shame really.

Close. In this context, I'd say it means that you're missing or ignoring a vital piece of information.

The phrase comes from the optic nerve thing like odiseo77 said, but its most common usage is to describe the area on each side of a car that you cannot see without turning your head to look, because it's not covered by rear or side-view mirrors.

How would you (in simple terms) explain the meaning of the word 'drive' as in 'a driven individual'? Thanks

I would use "motivated/motivation" as a synonym myself.

Can "mobilized" be considered? i.e. A mobilized man?