I bought my grandpas 1466 back a couple years ago , Brought it home never used it much past a hot bath. Carried 75 psi just running around no load.
Last summer I used it on a hay baler and noticed 0-10 oil psi at 2000 rpm ,so I took it off and put my 1256 on baler.
pulled it in my shop this fall and checked gauge with a snap on mechanical ,verified 0-10 at operating temp.
We owned it til 94 guy had a out of frame done in 98 at a reputable mechanic shop.
So i pulled filter housing checked by-pass all looks good.
Pulled regulator valve all good no broken springs all free.
Pulled pan all rods and main bearings labeled 10-98 no wear at all std.
Pulled oil pick up tube no cracks ,gasket good.
I put air on the oil psi gauge port and sounds like a leak above rear main bearing journal.
Motor sounds good no knocks. Less than 1500 on rebuild
Probably going to do a tear down but figured i'd ask