1 John 2:6 translation question

Knox Mike (KnoxM@rnd3.indy.tce.com)
Tue, 15 Apr 97 11:42:00 EST

Greetings,
I have been working my way through 1 John, and I ran into a roadblock on
Chapter 2, verse 6:

O LEGWN EN AUTW MENEIN OFEILEI KAQWS EKEINOS PERIEPATHSEN
KAI AUTOS [OUTWS] PERIPATEIN.

I am having trouble understanding how the infinitive MENEIN should be
translated here. Several translations, such as the NASB translate it as a
present indicative ("The one who says he abides in him, ought...."). My
question, is simply, why?
Also, according to Zerwick's Grammatical Analysis, the word OFEILEI normally
means "owe", but with an infinitive means "ought". Is this the reason that
verb MENW is an infinitive in this verse?

Thanks in advance,

Michael Knox