The smoking gun.
Last weekend I went to Dad’s place and grabbed the oil pump off the old 253. Been cleaning and blueprinting it since then. Last night I took the oil filter off my engine. I found a few threads of red cotton caught in the filter inlet….. WTF! Now I suspect a piece of rag/cloth is floating in the oil and blocking the oil pick-up. So my plan is to blow some air in reverse direction through the block into the pick up to try and release the blockage. Then drain the oil. Try and grab the blockage out through the drain hole. Going to try to borrow a camera to help.
PS Don’t think I used any red colored rags/cloth. (Have tried adding pics but give up. Doesn't like any file extension I try.)