Well, if there are only lockwashers and no locknuts, that would be your problem. Just to be clear, but a nylon locknut, I mean a stainless stell nut that has a nylon 'bushing' inside of the threads so when it is tightened it won't back off. You don't typically need or use lock washers with these nuts, though you would definitely need stainless steel falt washers.
You're going to ned to pick some up. As for access, unless you install an access hatch, you will have a water problem in that area.