SEM servo repair/replace

Looks like I did some damage to one of my servo's while tuning. I let it oscillate too long and it started smoking. Now it smells burnt and when I turn the shaft it turns freely except in one spot where it is very hard to turn once it gets to that point. I assume that is the area it kept oscillating at. Anyone know how much to repair something like this, what is most likely damaged, can it be repaired? It is the SEM MT30H4-44 model. There are several models on ebay ,none that are the same as mine.

thanks guys/gals