The San Juan Car Company AAR Type-E coupler is one of the
most realistic couplers in model railroading regardless of
scale. The coupler provided reliable operation when first
produced. Somewhere along the way, the die was damaged and
repaired. The repair wasn’t exactly right so the operating
characteristics of the coupler changed for the worse. A common
symptom of the problem is that the coupler won’t drop
the lift pin when the knuckle is closed. A sticking lift pin
prevents the coupler from locking so switching is made more
difficult. The revised coupler can be spotted easily by looking
at the rectangular slot on the bottom of the coupler body.
This is the slot where the lifting pin moves up and down.
The opening was enlarged when the die was repaired. This created
slop in the pin movement making the uncoupling balky. Study
the close-up photo of the two coupler sprues. The darker one
is an older version with a thicker back wall on the opening.
The coupler on top has a very thin back wall.