I don't always use straplocks but when I do I use Schaller. Stay classy my friends.
Seriously though, I was introduced to schaller locks as OEM on my US J Plus when I got it new in 90~91. I've replaced the strap on that bass twice because they became worn and frayed along the edges, but I've never had a strap side nut work loose, a guitar side button come loose, or a strap side unit come apart. The original set of locks that came with my J Plus are still working just fine and that was my only bass for 17 years and got used almost every day during that time. Practice at home, rehearsal, and playing out almost every weekend for most of those years. I've also got a couple more basses set up with them and while they have only been around a few years, all my schaller straplocks have been set and forget. Once mounted they have never needed adjusting, retightening or anything beyond just clip them on and go. I do check them when I do an IRAN on any bass equipped with them, but so far (knock wood) it's been 25 years and multiple sets and not a single problem.
If you are having issues with things coming loose, why blame the object when it's you who are responsible for the proper assembly of an inanimate object, so if it fails it's because you failed to use it correctly. Yes Virginia, defective parts do occasionally happen, but that is a completely different kettle of fish from nuts just coming loose. Oh and BTW, I don't use any locking aid on the nuts, just good old proper assembly and adequate tightening.
A couple of things with schallers that could possible cause you problems are too small a hole in the strap tab and not enough torque on the nut when tightening.
I've never had a strap fit a schaller strap lock without opening the hole(s) in the strap tabs. Push the lock through the hole then take an exacto knife and run it around the base of the lock, cutting away the excess strap tab. The idea is you want a nice flat laying tab around the lock barrel, but you don't want to gouge the hole too large as you have little margin for error here. Once you get the tabs properly trimmed, line up the U sections so they are pointing up when the bass is strapped on. This usually won't be straight up in line with the center of the strap. Once you have that set right, get a pair of 6 or 8 inch channel locks, AKA water pump pliers, AKA Tennessee socket set, and adjust them so you can get a death grip on the U cradle without moving it around in the strap tab. Then, get a 4 to 6 inch adjustable wrench and tighten the chit out of the straplock strap tab retaining nut. If you use the short tools chances are good you won't be able to crush the U cradle or strip the retaining nut, but will still be able to develop enough leverage to get them tight enough to never need worry about them coming off. If it makes you feel better, or you don't trust your wrenching skills, employ some kind of thread locking product, or a drop of CA or nail polish after you've got the nut fully run down.
But please do us all a big favor, if you can't do the job right and it fails as a result, please quit blaming the product. Installed correctly they work without problems, and will do so for a very long time.
