Since new my integral cases leaked. The lid pressing on the seals in time caused them to settle and lose their water tightness. This simple solution works well and has fixed the problem.
To simplify the explanation I refer to the "lid" the part that opens and the section of the case that fixes to the bike the "base".
There is a "lug" which is the part of the lock that is pop riveted (2 rivets) to the "base". With a sharp point I scribed around the lug so I would know the original position when reassembling then drill out the 2 rivets, removed the lug, and elongated the holes in the lug. The plastic they use in the lug is very difficult to enlarge with a drill so I used one of those rotating leather punches and snipped a little plastic away from each side of the hole. The reason for doing this is so the lug can be moved in and out on the base to get sufficient tension to prevent leaking when the lock cams shut.
Bought some 3 mm or equivalent "cap" bolts (Allen head bolts) washers, and nylok nuts from the local hobby supplier. You need to use bolts with Allen type heads as bolt the heads are in a recessed hole inside the case.
Reassemble by inserting the bolt from the inside of the case with lug then washer then nut on top. I applied a little silicon grease under the lug to discourage water working its way down the bolt thread and into the case. The main part of the lock attached to the lid will clear the bolt heads when clipped over so long as the bolts length is kept to a minimum. Since the original position of the lug was marked the lug can be initially tightened down a fraction closer towards the bike.
Caution..... the lug only needs to be moved slightly from its original position to get a proper seal you don't want to compress the seal more than necessary and don't over tighten the nuts. Trial and error using a garden hose will let you know the correct position of the lug. This really doesn't take long to do and allows you to adjust the lid tension anytime.
If you wanted a quick fix you could just glue a piece if something to the inside of the lug causing the lock to cam in tighter but this does not give any adjustment. Also don't over pack (probably the main reason for leaks) the case as this distorts the case lid and causes improper sealing.
I have also removed the "press studs" on the strap that stops the lid opening too far and fixed it to the base of the case with small bolts. I had the bike on the side stand once and opened the left hand side case the lid slipped from my hand the press stud unclipped and the painted lid hit the ground scratching it. Since I always use the internal bags I have never needed to open the lid further than the straps permit. So unclipping is not necessary. Also the pop rivet securing the male section of the press stud to the base of the case becomes loose with use.
Another problem to be aware of particularly with the left hand case. This is more a problem for the inexperienced user but it is possible to attach the case to the frame and lock it on and the case not to be fully clipped over the frame at the back of the frame rail. This causes the case to sit up slightly at the back and is not always obvious and could cause the case to fall off if a pot hole is hit. I always double check that the cases are fully clipped over the frame rails when I put them on.
It may be obvious, but I always lock the case to the bike and keep the lid locked. I often think it is the reason why so many cases are lost while riding.