Last summer I replaced a cap on this '88 Trane unit when it stopped
running. It was actually the 2nd time I'd replaced that cap. Once the
cap was replaced it ran fine. Cooled the house off quick, not huge
impact on the power bill given rate hikes over the years. Ran it a few
times for heat briefly during the Winter, didn't notice any problems.
Just now when I tried to fire it up on A/C again, no cooling. So,
having gone through this drill twice before I immediately went to look
at the cap. It's not bulging like the previous 2 were before but one
of the spade connectors has severed from the wire and there's obvious
arcing residue on the contacts and melting of the plastic fitting
around the contacts the severed spade was attached to. On that side
the contacts are also very rusted while the contacts on the other side
are still shiny. I can also feel oil on the outside of the cap.

Not a big trick to get another cap and solder a spade connector back
onto the wire, but I wonder what caused the arcing? The A/C ran like a
champ when it was running last summer after the cap was replaced and I
visually checked it a time or two over the next couple of months to
see if I could see any issues, didn't see anything that caught my
attention - but this makes 3 times in a couple of years I've had
issues with that cap, albeit not the same identical issue at least
from an eyeball standpoint.

I've had the cap mounted sideways, simply because the strap on the
unit for the factory cap is oriented that way. Should it make any
difference which direction the cap is oriented?

Thanks for all assistance and wisdom.