Modifying existing animations?

Exported from 2009 or from 6?!

From 2009 to .ma, from .ma to 6, and then to .gr2. Everything as in zahar0z's guide.

Added after 11 hours 39 minutes
I solved the problem. I had an extra bone from somewhere. I deleted it, re-exported everything, and the animation started working. But, unfortunately, the animation is still not quite right, so I'll have to work on it some more.

Added after 3 hours 48 minutes
Now the problem is that the animation doesn't "drift". Since I have a new idle animation, the hooves should be in the same place at any point in the animation. I don't know how to lock their movement (if it's even possible), so I have to adjust them at the beginning, middle, and end so that they don't drift in different directions between these keyframes.

Added after 8 hours 7 minutes
Now there is another problem - since I have an idle animation, it should repeat infinitely. It does repeat, but with a delay of one or two seconds between cycles. How can I fix this? No one knows. The animation is only 60 frames long and lasts two seconds (30 frames per second). Do I need a longer animation, or is there something I need to change in the configs or the animation itself?