On the left is the worn thrust bearing of the Type L2;
On the right, it's the Type L0's thrust bearing, where someone has attempted to compensate for wear.

The Type Pre-L had a little different arrangement for taking care of end thrust.  The Type L uses a single, hardened steel ball to handle the thrust; perhaps this example of the Type L2 once did as well ...

I'm planning to attempt to fix this situation by adding a ball race to each of these two drills, which I ought to be able to do without permanently changing anything from the original ...

Note that the pinion teeth on the right are far more worn than those on the left-hand drill are.  That may be the result of different patterns of use, either in the type of drilling or in the manner of care, with less lubrication and larger end forces applied to the Type L2 in this example.