500mg is okay since you already have it. Carnitine is not 100% absorbed anyway.

Just take 500mg a day to start. See what happens.

I'd take 1000mcg methylB12 just as insurance ..daily on an empty stomach. Dr. Snow found some people in his study who were in the normal range but not high, did improve on extra B12.
I have that quote on the B12 thread:

http://neurotalk.psychcentral.com/post698522-70.html

Because B12 is so safe to use, trying it can't hurt. You have those "lesions" which may need help remyelinating.

It is a sad shame that doctors don't understand the biochemistry of the body. In fact we are all complex chemical factories where movement of ions, messenger RNA, and building blocks like Omega-3 fats, and choline, are used to repair daily wear and tear and injuries to all our tissues.
Doctors will give toxic drugs that damage us, as "treatments" but they fail to understand the mechanisms of healing on a chemical level! sigh.