I called Ingersoll-Rand. The hoist was made in 1974. Since it was made
after I was born, I consider is almost new. The tech guy told me the
same thing as I was told here, most likely it is a bad, rotted seal
and I need to find out which one, and they will sell me a
replacement.

They have a replacement control arm for not too much (relatively
speaking -- the hoist cost me $35 and the replacement control arm is
$78), and the seals.

i