Decide if the "personal a" is necessary in the following sentence.
necesito un abogado.
the "personal a" is necessary.
the "personal a" is not necessary.

The "personal a" is not necessary in that sentence. If you say: "Necesito un abogado" it means "I need a lawyer". In the same sense, if you say "Necesito a un abogado" it still means "I need a lawyer".

If you include the personal 'a' or not, the meaning of the sentence will remain the same. Therefore, the peronal 'a' is not necessary.

The "personal a" is not necessary, but it is optional.

Necesito un abogado or necesito a un abogado.

Both are correct sentences

I need a lawyer.

Explanation: "un abogado" is the direct object of the verb "necesitar". In Spanish the preposition "a" is used when the direct object is a person and is omitted when the direct object is a thing. Since "un abogado" is a person,  this direct object should have the preposition "a", but if the preposition is not used it is considered as an object, an instrument, not a person. It is an option.