For installing straplocks onto a thick leather strap, with either Schaller or Dunlop straplocks, it's handy to have two sets of needle nose pliers. For Dunlop, one set of pliers to push down the washer, the other to force the C-clip onto the post. For Schaller, one to hold the cup, the other to tighten the nut.
Also, for Schaller, a dab of loc-tite or clear nail polish will keep the nut from coming undone. Clear nail polish is great because: a) it's clear. b) it's strong enough to hold the nut on, but brittle enough to break and clean up when you want it to.
As far as the screw is concerned- the toothpick and wood glue is the best method. The reason for the glue is so that the screw is biting into material that's bound to the body, not just relying on the pressure of the screw against the wood. The "best" method is to fill the hole with glue, insert the toothpick(s), break them off to length, wipe up excess glue and screw the screw in. What you're doing is binding the toothpick to the sides of the hole. The glue will not bind to the metal screw- only the wood. The screw is biting into the wood that is bound to the sides of the hole.
Although they're both "good" units, I feel the Schaller is "better."
I used Dunlops for over 10 years. I'd had a few failures of the Dunlops, but I always attributed it to "user error," that I hadn't seated the unit properly. However, after I had nearly dropped a 45 year old Les Paul when I KNEW the locks were seated well and proper- I looked back into it. The Dunlops are held on with either 2 or 4 ball bearings held in with spring tension. The bearings fit into a trough on the female end. If a bearing fails, the spring fails or there's junk in the trough, or if the shaft wears, the unit can fall out.
The Schaller is a cup bearing the weight of the guitar. It is also redundantly held into the cup by the spring loaded plunger. If the spring loaded plunger fails, the cup is still supporting the instrument. The cup is not going to fail. I've actually smacked a Schaller with a hammer to see what it takes to break the cup. The only ways for the Schaller to fail is if the nut comes undone- if you check the nut and/or secure the nut to the unit with loc-tite or nail polish, it's not coming off, and if the button itself wears down too far. That's when the guitar end starts looking like a rounded off nub instead of the way it looks.
I've been using Schaller straplocks since 2002 and have not had one single "failure" yet. When I was using Dunlops I had at least 3 failures in the first 5 years of using them.
