my extruder seems to crack my fondant/gpaste. It looks as if it is going against the grain - just cracked all around. I've tried oiling the extruder, extra oil in the medium, nothing works! Please advise. Thanks

Knead some solid shortening into your fondant/gumpaste. If it keeps happening, the piece of fondant you're working with may have already dried out too much. Try a fresh piece.

DianeLM is right, you must knead some shortening into the fondant or gumpaste, it will also make it easier to extrude.

Yes, you need to add shortening to your fondant. I've found that you have to add quite a bit sometimes.

Your fondant has to be mixed with shortening until it is really soft, especially if you are using the large extruder gun.

Microwave the piece going in for up to 10 seconds, then cover in a small amount of Wilton glycerin (it feels like a baby oil coating), then extrude.

I've been REALLY happy with my results after doing this.