For the sake of the forum I tried to figure out why so many of you are having issues installing your PO rubber strap.
O.K here is what I came up with. I tried installing the rubber strap with a new set of spring bars. It was a bear!!!! I see what some of you are having problems with. First of all you need the correct spring bars in the diameter 1.78mm. This is a double shoulder spring bar in size 22mm for the 45.5mm Planet ocean. Do not use a single shoulder spring bar. (See pic below) I want you to first test fit your spring bars without the strap. Try it and see how easy they fit in the holes of the lugs. The PO has very small holes drilled into the lugs. Some after market spring bars have a larger nipple end and it may not slip easily into the holes of the lugs. Either buy other spring bars or file the end diameter of the ends (just the very ends)of each spring bars. Once you are sure they fit correctly, try installing them as seen in the pics below. I am using a spring bar tool with a small forked end. First slide one side into the opposite hole locking the spring bar into the first hole. Now once you compress the other side and slide the spring bar between the lugs, apply pressure on the strap by using the locked in spring bar side as leverage and push. You may have to move it around a bit. Use a good light so you can see the hole you are aiming for. If you positively cant get it into the hole. You may have to bend the spring bar ever so slightly. This will give you less compression of the rubber strap. Ideally you want the strap to be pushed against the case firmly to avoid gaps.
Note the different style of spring bars. The one on the left is the correct one. You want a double shoulder end spring bars in diameter of 1.78mm. 22mm length for the 45.5PO. Not sure the length of the 42mm PO.