What are "gator track" bevels? I'm not familiar with that particular description although I think I know what you mean.
What process are you cutting with? Oxy-acetylene? Oxy-propane? Plasma?
Is your machine too close to the cutting so that heat is warping the drive wheels after 1 or 2 cuts?

How thick are you beveling? You might want to preheat before cutting.

Is the wheel aligment correct in the track? If it isn't, the machine could try to "climb" the grooves and then drop back, particularly if the tracks get warm. That might not be very noticable but could shake the torch. I'm not sure about Beetle track machines but Victor and Airco have lock nuts on the "steering" wheels. We usually leave them slightly loose to help the machine ride in worn tracks better.

Do any of the wheels have flat spots?

Is your torch gear rack bar extended out too far? That would magnify "small" problems.

If you are using oxy-fuel, is your flame set right? Sometimes an operator will set the flame slightly oxidizing (pale blue preheat cones) to allow a faster cut start. That won't tolerate any wiggling in the torch and you lose the cut a lot. It's better to have the flame almost carburizing but the preheat cones should be bright blue. Slower to start the cut but it tolerates "bumps" and "wiggles" much better.

Can't think of much else right now. Obviously something has changed for you if all worked OK before now. Hope this helps.
Chet Guilford

I thought I was the only one to tell my students that it looks as if a snaggle tooth gator had chewed on the steel.

Most of the time the gator bites (serated cut edge) appears because the flame is not hot enough (read that as tip too small or wrong gas pressures) or the travel speed is too fast for the amount of heat/tip size. Students want to run wide open, they think it's cool.