The number one hole commonly fails more often. It is actually a different size on some engines.(I said engine instead of motor just for you P.E.)

P.E. is right on top of things because I forgot that you could pull the number one piston/rod by pulling the lower oil pan.

If it were mine, I think I would be tempted to pull the head and the piston for a little exploratory surgery. If the cylinder is good, not scored or excessively tapered, a piston might very well get the job done. Since the other holes seem to be in good shape, this might work out pretty good.

I suspect the piston because I had one noisy before my 240D engine came apart at 380,000. Turned out the hole that was rattling had a piston with ring land faliure that was just about ready to seriously let go.

If you have a good, reasonable machine shop to do the head, this could be a cost effective repair if you can do the work yourself.

Best of luck,