Until the last year the leaves looked healthy and lush. It has gotten 4 leaves in the last year. These leaves have wrinkles near the middle, and they are not as large as the older leaves. The older leaves have brown edges.

The plant does not look healthy or happy.

We live in WI so I leave it inside in a 12" plastic pot with a draining saucer. I usually do not fertilize my house plants during the summer, but from Oct. - May I give them Schultz's Liquid Plant Food 10-15-10. My other house plants look decdnt and do not have an damaged leaf problems.

Any Help or suggestions?

My guess however is that it is becoming root bound, if so just re-plant to a larger size pot. When doing so cut into the roots to encourage new growth. Don't fertilize it for at least a month after transplanting with your normal nitrogen based fert, as this will burn the freshly cut roots. Instead mix a bit of bone meal into the soil. This will help establish new roots.