Quadricep Imbalance. How to strengthen the "teardrop" Vasto Medialis part of quads..

[Inchworm]

Hi,

I have been experiencing some knee pain that comes and goes. Right now it feels better but I have finally figured out, thanks to some of you, that my quads are imbalanced. My outer quad as a very obvious outer sweep, but my teardrop or inner quad is barely there. I've read up on this and it can cause some very uncomfortable knee cap tracking problems. What exercises or dvd's have some good exercises for this particular area of the quads. My outer quads develop very easily and I used to do leg extension machines at gym, but no longer go to a gym, so I guess that area has been neglected.

Thanks,

Kelly