Yes, it took me quite a long time and a lot of searching to find it, but it is fixed.
Here is what I found-
The loss of pressure was in the oil pump. I disassembled it several times and missed the problem every time. There were several shards of metal in the pressure regulator on the oil pump.They came from the bolt that came loose and got into the timing gears.
If you would like, when you are ready to start working on the problem, I can offer the benefit of my experience. I've learned that if you disassemble things in a certain order, it is about 10 times easier. I hope that I can save you from having to go through the same learning curve that I did.
What do you have for a service manual for your Oliver? I started out with the only one that I knew about. It was originally published by Oliver- it is pretty incomplete. During all of my searching for information, I found the original Fiat Factory Service Manual in England. It has about 10 times the amount of info that is in the Oliver book. I was able to download it and have it on my computer. I can share it with you if you need it.
Jim