Not sure it would have helped, but the Op manual says to drain the 'oil filter drain pipe' before pulling the filter. It seems this is pretty well ignored, judging by the Cubs I have seen. It also says to inspect the small metering hole at the end of the oil filter retaining bolt, if plugged with will stop all flow through the filter. A Cub does not filter all the oil. Since the oil pressure gauge is in the filter housing I wonder if that being plugged would build up pressure??
It is also a good idea to flush the filter housing, put the bolt back in and use kero, draining it though the pipe. Good idea on any 'new' Cub. I even found the drain pipe cap in my last Cub! Another I found the copper washer for the bolt.
Glad you fixed your problem. Thanks for filling us in.
Edited to add the picture: flushing the filter housing, found a 'stray' pipe cap in there! Note the cap 'bolt' keeps the junk out of the oil pan and down the pipe....
1971 Cub (Rufus) 1950 Cub (Cathy) 1965 Lo Boy Fast Hitch (Nameless III) 1970 Cub 1000 Loader & Fast Hitch (Lee)