The Atlas O turntable is more like a cake spindle than a true turntable.
No Pit, the top is a platter that spins on a bearing in the center.
I have seen a nicely detailed one with painted in rough on the platter to simulate the pit.
As noted, it is not particularly strong, being all plastic.
Still, for the comparable amount of money it's not a bad TT, just remember it's not made to turn a 15 pound engine.
I suspect a larger diameter thrust bearing under the outer portion of the platter would fix it nicely, except you still wouldn't have a real pit.
And I would gear the motor down a bit more for the power needed to turn heavy engines.